Two Iranian diplomats recently expelled from the Balkan nation of Albania were tied to an alleged plot to attack an exiled group inside the country earlier this year, a source with knowledge of the matter told The Independent.

Albanian authorities booted out Iran’s ambassador to the country and another diplomat, accusing the two of "violating their diplomatic status," amid an ongoing regional intelligence and diplomatic battle between Iran and the US its partners.

The source with knowledge of the matter said the expulsions were connected to an aborted March 2018 scheme by two alleged Iranian members of the Revolutionary Guard’s Quds Force, its foreign secret operations branch, caught planning “an explosive” attack against the base or personnel of the Mujahedin-e-Khalq, or MEK.

US officials on Wednesday praised the decision by the Nato country to expel the diplomats. US National Security Adviser John Bolton wrote in a Tweet that the move signalled to Iranian leaders that “their support for terrorism will not be tolerated.”

Tirana’s move follows diplomatic rebukes of Iran by Denmark, France, and Netherlands amid allegations of using diplomatic facilities to carry out alleged terrorist operations targeting dissidents living in Europe, including the MEK and Arab exile groups.

It remains unclear when the diplomats were expelled. President Donald Trump, in a letter dated 14 December that surfaced on Wednesday, lauded Albanian prime minister Edi Rama’s “steadfast efforts to stand up to Iran and to counter its destabilizing activities.”

Trump administration officials appeared to announce the expulsions even before Albanian counterparts. The news website Tirana Echo opined that the expulsions “are expected to further strengthen bilateral ties between Tirana and Washington, a much awaited sign by Albania’s leadership who had recently been concerned by President Trump’s lack of attention towards the Balkans.”

Iranian officials have described the moves to punish its diplomats as pushed by hardline US officials hostile to the nuclear deal and seeking war with the Islamic Republic. Iran’s foreign ministry spokesman Bahram Ghasemi on Thursday denied the accusations, insisting that “Albania has become an unintentional victim of the United States, Israel and some terrorists groups,” according to the official Islamic Republic News Agency.

A source close to the Iranian government described the Albanian move as a result of pressure by the US, which is seeking to weaken ties between Tehran and Europe forged during the creation of the 2015 nuclear deal. He also noted media reports that Israel had a hand in the Albanian expulsions, and potential financial ties between MEK and Mr Bolton when he was a hardline conservative activist before joining the White House – Mr Bolton has spoken at MEK rallies, and has never denied receiving money from the group.

What's happening in Albania has only proved how big Tehran's networks in the Balkans are Ruslan Trad, researcher on Iranian influence in the Balkans

But close observers of Iran describe a resurgence of clandestine operations across Europe and elsewhere targeting Iranian dissident groups. Others have noted Iran’s burgeoning efforts to establish clandestine networks in the Balkans. Albania in particular has a Bektashi religious minority with ties to the Shia branch of Islam practised as the official religion in Iran.

“What's happening in Albania has only proved how big Tehran's networks in the Balkans are,” Ruslan Trad, a researcher and journalist focusing on Iranian influence in the Balkans, told The Independent.

Those briefed on the matter say tensions between Iran and Albanian authorities have been building for several years, as the country increasingly becomes a battleground between various intelligence services.

"Indeed there was American pressure on Albania, but Tirana has its own reasons to act," said Mr Trad. "Israel considers Albania as a possible intelligence base. And Iranians also see Albania as a possibility."

Some Albanian media cited unnamed sources saying that the expulsions were connected to an attempted bomb plot during a November 2016 FIFA World Cup qualifying match between Albania and Israel in the city of Shkoder. Around 20 people were arrested in Albania and Kosovo, with nine Albanians sentenced in May to more than 35 years prison.

Inside the MEK’s state within a state

But the source with knowledge of the matter said the expulsions were unrelated to the match plot, which was originally linked to Isis members. Mr Trump, in his 14 December letter to Mr Rama, appeared to allude to the MEK connection, referring to Iran’s “efforts to silence dissidents around the globe.”

The MEK, a cult-like Iranian group of 2,000 or 3,000 hardcore members and more supporters among Iranians in the diaspora, fought against Tehran for decades from a base in Iraq but moved in recent years to Albania under a deal brokered under President Barack Obama.

Iran has been rankled by the presence of the group in Albania, where it has bought a massive property in the countryside and runs information operations against the Tehran government from inside a heavily fortified compound.

The two alleged Quds force operatives were caught by Albanian authorities and expelled. The Iranian embassy at the time denied allegations that the two men were involved in any type of clandestine operations, describing them in a 22 March press release as “documentary filmmakers.”