Turkish President Recep Tayyip Erdogan's recent re-election is fueling concerns about his growing powers not just in Turkey but here in the U.S., according to experts who believe he's determined to spread his controversial brand of Islamist-nationalistic fervor through a network of mosques and religious centers.

Some of that concern is focused on the Diyanet Center of America (DCA), a mosque and Islamic center in Maryland, just outside Washington, D.C. The DCA was built with the strong support and funding from the Turkish Presidency of Religious Affairs, or Diyanet, which under the 15-year Erdogan adminstration has pushed for the building of mosques and Islamic centers around the world.

Erdogan himself attending the opening of the $110 million center in 2016. But while the DCA's primary goal, according to its website, is to "providing religious services without regard to politics," critics say that's not the case.

“These mosques are not places of worship,” charged David L. Phillips, Director for the Program on Peace-building and Rights at Columbia University’s Institute for the Study of Human Rights. “They are centers for political mobilization functioning like madrasas, distorting Islamic and radicalizing youth.”

Poised in a quiet neighborhood in the town of Lanham, Md., across the road from a small church and a cluster of humble homes, the DCA fills an entire block, with a series of impressive buildings. And it's from this location that critics say the Turkish government spreads Erdogan's brand of Islam, spies and gathers information for his national intelligence service, and tracks Turkish-Americans who they suspect of following Fetullah Gulen, a Pennsylvania-based cleric and one-time ally the president has named public enemy number one in Turkey.

Erdogan has been running Turkey under emergency rule since a July 2016 coup attempt - which he blames on Gulen - and along the way has imprisoned tens of thousands of Turks from the ranks of the civil service, military, judiciary, and education systems. Erdogan has demanded the U.S extradite Gulen, but those demands have been denied, citing a lack of sufficient evidence.

“Gulen was one of the closest political allies of Erdogan between his party’s ascent to power in November 2002 and their dramatic fallout in December 2013,” explained Aykan Erdemir, a senior fellow at the Foundation for Defense of Democracies. “Erdogan pursued an effective campaign to first criminalize the movement and then to designate it as a terrorist organization. Today, a majority of the Turkish citizens see the Gulen movement as a terrorist entity.”

The Turkish flag flies high on the lush grounds of the DCA, whose imams and female chaplains are assigned through the Diyanet headquarters in Ankara, the Turkish capital. And the DCA is one of more than 20 mosques under the Diyanet umbrella, which most of them located in the Northeast.

But many Turkish-Ameicans who support the Gulen movement – or simply don’t agree with Erdogan's rule - say they stay far away.

“Gulen supporters don’t go to the Maryland mosque because they have a very credible fear of being harassed, intimidated or attacked. This is happening in all Diyanet-funded mosques across the U.S.,” claimed one Turkish journalist in the U.S., who previously worked for a pro-Gulen publication. “Many of the Gulen supporters were not permitted to pray, and ‘Gulenists are not permitted’ banners were hung on walls. But people fear more to be abducted than intimidated.”

A spokesperson for the Turkish Embassy in Washington did not respond to specific questions for this story. But the spokesperson provided a statement claiming the “group in question is not an innocent one focusing on education and charity activities as they prefer to disguise themselves, but rather a terrorist organization which attempted to overthrow the democratically elected government of Turkey with a terrorist coup attempt that cost the lives of 249 innocent Turkish citizens and injured over 2000 people.”

“In that regard, the group should be called with its proper name: ‘Fethullah Terrorist Organization – FETO’ and not as the ‘Hizmet movement.’”

In addition to the “terrorism” tag, the Turkish government describes “FETO” as a “cult-like movement” founded upon a “deeply troubling” ideology that masquerades as a pacifist Islamic doctrine, but cautions that those who have studied his “original” teachings warn of the “anti-secular, anti-Western” sentiment.

The embassy vehemently denied any accusations of surveillance.

“Neither the Turkish government nor Turkish citizens have been involved in spying activities against any individual living abroad,” the spokesperson said. “This is yet another example of the smear campaign initiated by the members of FETO. All allegations mentioned in your query therefore are totally false and groundless.”

But some strongly beg to differ.

Abdullah Bozkurt, President of the Stockholm Center for Freedom – an advocacy organization created by a group of Turkish journalists who live in self-exile in Sweden – cautioned the family members and associates who remain in Turkey end up paying the price for surveillance abroad.

“The profiling and unlawful intelligence gathering in diaspora put not only Gulen people but all other critics, opponents and dissidents at risk of imprisonment if they are to return to Turkey, confiscation of their assets, jailing of their relatives with guilt by association,” Bozkurt alleged.

Earlier this month, the Stockholm Freedom Center accused the Erdogan-led government of intensifying its “intimidation tactics” and “refugee espionage” targeting alleged members of the Gulen movement abroad,” after the state-run newspaper Anadolu news agency published information about members using an Episcopalian church in New Jersey for their Ramadan prayer given the mosque concerns.

“Having to use a space provided by a church is not unique, but it is rare,” another member of the movement in the U.S. said. “There are many examples of relatives of supporters being targeted. This is not just a fear, it is a reality.”

Some experts argue the Turkish government’s concerns over the Gulen movement simply make sense.

“Because the government believes that the Gulenist movement was behind the coup attempt, it is understandable that Turks will take a hostile view of its members while being suspicious of their motives,” noted Barak Barfi, Middle East expert and Research Fellow at the New America Foundation. “Turks living abroad, like most expatriates, are largely loyal to the state and willingto do its bidding.”

The Diyanet and Diyanet America did not respond to repeated requests for comment for this story.

Concerns about Diyanet activities are even more widespread in Europe, where several countries have investigated the mosques and their activities.

“Germany, Belgium, Austria, Netherlands, Switzerland, Norway and Sweden have carried out investigations of Turkish imams, appointed and paid by the Diyanet, for spying on behalf of Turkish intelligence against Turkish citizens living in their countries, who are considered enemies of Erdogan,” said Ahmet Yayla, Associate Professor at Georgetown University’s Center for Security Studies and the Edmund A. Walsh School of Foreign Service.

TALIBAN PRISONERS EXPLOIT RELEASE LOOPHOLE WITH FAKE MEDICAL CLAIMS

Austrian officials recently announced they would shutter seven mosques and remove up to 60 imams funded by foreign countries, a violation of a controversial 2015 Austrian law aimed at tackling “Islamist radicalism.” A series of controversial images involving children from inside the mosques sparked controversy in Austia, sparking debate over what was going on behind closed doors.

“It has been known now for some time that many of the imams who are running these mosques in Austria have been promoting Islamic radicalism,” said Alon Ben-Meir, professor and senior fellow at New York University’s Center for Global Affairs and Senior Fellow at the World Policy Institute. “They are considered servants of the Turkish government.”

And in March of last year, Austrian lawmaker – the now ousted Greens politician Peter Pilz – alleged the Turkish “intelligence network” – which was already under investigation by German, Austrian and Swiss authorities – was far broader than just those three European countries.

Pilz released documents, purported to be on both Diyanet and prime minister’s office letterhead, seeking information on Gulen followers. One such letter, dated September 20, 2016 and viewed by Fox News, was allegedly sent to 38 Turkish embassies in various countries, and signed by Halife Keskin, acting-director general of the Diyanet’s external affairs department.

The letter asked imams deployed abroad to send “detailed reports” about the Gulen movement – its members, their schools, connections to NGOS, associations, cultural activities, human resources and any other relevant tidbits of information.

IRAN AIMS TO BE KING OF THE HILL ON KEY STRATEGIC MOUNTAIN IN IRAQ

Around the same time as the release of documents, an official in Turkey’s Vienna embassy, Fatih Karadas, told Austrian newspaper Kurier it was their “religious duty to conduct investigations into whether Turkish-origin citizens were influenced and misused or radicalized by Gulen” - while denying that constituted spying.

Turkish officials called Pilz’s accusations “completely false.”

A few months earlier, in late 2016, Turkey recalled its religious affairs attaché of the Turkish Embassy in The Hague, Netherlands – Yusuf Acar – after he received a “deportation warning” and was accused of collecting intelligence on the Gulen movement. The Diyanet staunchly denied charges it was illicitly gathering intelligence.

Around the same time, authorities in Brussels, Belgium also stated several mosques had received requests from Turkish authorities to spy and inform on Belgians of Turkish origin suspected of being active Gulen followers.

And in neighboring Germany, Green politician Volker Beck filed a criminal complaint in December 2016 against the Turkish-Islamic Union for Religious Affairs (DITIB), Germany's largest Islamic group, with over 900 mosques tied to the Turkish government's Diyanet, over concerns that data was being collected illegally.

The deputy chairman of the German Chancellor’s Christian Democratic party, Armin Laschet, promptly called for the expulsion of all imams associated with the DITIB. A spokesperson for Laschet told Fox News they learned in December, 2016 that “various consulate generals of the Republic of Turkey were collecting information from imams of the Islamic governing body DITIB, among others, about alleged supporters of the Gulen movement living in Germany and sending this information to Turkey at the orders of the Turkish religious authority Diyanet in Ankara.”

German police went on to raid the homes of four imams connected with the DITIB last February. The raids were part of a wider investigation into illegal espionage on supporters of Gulen. No arrests were immediately made.

The investigation closed in December 2017. Volker Beck, German lawmaker and religious spokesperson for the Green Party who filed the initial complaint, told Fox News that no charges were brought forward because “all suspects fled the country.”

Erdogan has repeatedly denied any wrongdoing and accused the country of adopting “Nazi practices.”

Yet more issues are being raised. The Office of the Attorney General (OAG) of Switzerland recently issued national arrest warrants for two Turkish diplomats accused of abducting a Swiss businessman in Turkey suspected of having ties with the Gulen movement. The men were reported to have been working at the Turkish embassy in Bern – one as press attaché and another as second embassy secretary – at the time of the incident, which occurred around one month after the coup effort.

Criminal proceedings have reportedly been in progress against the men since March 2017, after the Federal Department of Justice and Police authorized the OAG to take respective legal action.

A representative for the OAG in Switzerland told Fox News the two suspects “do not and did not enjoy diplomatic immunity.” Turkish officials have denied the allegations.

Despite the heavy criticism of Erdogan’s authoritarian rule, supporters note he has an upside in a region ripped apart by chaos and terrorism.

“His government is a stable island in a regional sea of chaos where no less than five states face an al-Qaeda/ISIS threat. Washington has long proved willing to tolerate authoritarian leaders if they can bottle up the jihadist threat,” Barfi said.

Meanwhile, Ottoman-style mosques continue to sprout – and not just in Europe and the U.S. Even Cuba – where only 0.1 percent of the population is Muslim – received its first ever mosque, with another on the way, courtesy of Turkey.

“The Diyanet started to receive substantial funding from state resources. They now have the financial means to invest in foreign countries where there is a Turkish diaspora to provide religious services,” noted Sinan Ulgen, chairman of the Istanbul-based Center for Economic and Foreign Policy Studies. “But there are also claims that the Diyanet funded mosques are being used for political purposes to boost support for the AKP abroad.”