Hundreds of refugees and migrants are stuck in "no man's land" on the Hungarian-Serbian border following tighter border controls and several deportations from Hungary.

"The conditions are unacceptable here," Balint Bardi, an independent Hungarian journalist, told Al Jazeera by telephone from the Serbian side of the border.

Because the razor-wire border fence is built within Hungarian territory, the refugees and migrants are stuck in camps in "no man's land", an area which is not Serbian territory and that Hungarian authorities do not administer.

"There is a huge queue of people waiting for entry to the transit zone to request asylum [in Hungary]," Bardi added, estimating that around 500 people were stuck in two camps on the border.

The crisis on the border comes days after Hungary introduced stricter border controls that allow police to effectively deport refugees and migrants found in Hungarian territory within eight kilometres of the border fence erected last September.

"The goal of the new border protection system introduced along the Hungarian-Serbian and Hungarian-Croatian borders on Tuesday is to prevent illegal immigrants from being in Hungary, but to allow those who wish to submit requests for asylum," Gyorgy Bakondi, chief adviser on homeland security to Hungarian Prime Minister Viktor Orban, said in a statement on Wednesday.

At least 151 people were caught within the 8km area and returned to Serbia on Tuesday morning, he said.

READ MORE: Hungary's border war on refugees

Speaking to local media, Bakondi said some 350 people were waiting for their asylum applications to be processed in transit zones on the border.

He added that more than 6,000 police officers have been deployed along the border, and that an estimated 1,060 refugees and migrants had attempted to cross the border since the new measures were implemented on Tuesday.

During a news conference on Tuesday, Major-General Tibor Benko said the Hungarian army is "carrying out patrol duties and air and land reconnaissance, medical duties in transit zones, and are also prepared to perform crowd control tasks".

'Not easy'

Bardi said the huge amount of police on the border have made it nearly impossible for those who intend to breach the fence - which spans the length of the 175km border with Serbia - and enter Hungary.

"The area is full of police on the Hungarian side," he said. "It's not easy for people who are trying to cross irregularly."

Lydia Gall, a researcher for Human Rights Watch, said the Hungarian measures allow police to effectively carry out push-backs, a practice which violates international law.

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"These are basically summary returns because there is no [legal or judicial] procedure involved," she told Al Jazeera. "These measures are illegal under refugee law and international law."

More than a million refugees and migrants reached European shores by crossing the Mediterranean Sea last year, according to the UNHCR, the United Nations refugee agency. More than 231,000 have made the dangerous journey so far this year.

The number of those arriving in Western Europe via the Balkans route has decreased since March, when borders were sealed across the region following an agreement between the European Union and Turkey to halt arrivals.

While the Hungarian government formally considers asylum claims at transit centres on the border, applicants are overwhelmingly rejected.

Of the more than 18,000 asylum applications in Hungary, only 76 people were given refugee status between January and May of this year, said Nora Koves, a human rights expert at the Budapest-based Eotvos Karoly Policy Institute.

"The government has absolutely built a legal fence in addition to the physical fence on the border," she told Al Jazeera, explaining that authorities accept only 15 asylum applications a day.

"The process is very slow, and there is basically no chance to get asylum."

Refugee referendum

Earlier this week, Hungary announced it will hold a referendum on October 2 to decide whether the country will honour an asylum seeker quota decided by the EU.

PM Orban's right-wing government and one of the leading opposition parties - the ultra-nationalist Jobbik - oppose the EU programme to relocate 160,000 refugees across the union.

READ MORE: Hungary sentences refugees for breaching border fence

In a statement released earlier this week, President Janos Ader said voters will be asked: "Do you want the European Union to be entitled to prescribe the mandatory settlement of non-Hungarian citizens in Hungary without the consent of parliament?"

Koves argued that the referendum is part of the government's politicisation of the refugee crisis. "It's a referendum against refugees and migrants, but they also view it as a kind of 'freedom fight' against the EU."

Serbia's B92 news agency reported earlier this week that Hungary plans to deport up to 17,000 refugees and migrants back to Serbia.

"Serbia will not imitate Hungary and will not stage a 'show' on its borders," Serbian Prime Minister Aleksandar Vucic said in Belgrade on Wednesday, as reported by the regional BalkanInsight news site.

Follow Patrick Strickland on Twitter: @P_Strickland_