Hungary said Sunday it is halting entry to its border “transit zone” camps for asylum-seekers over coronavirus fears after Turkey began letting migrants head toward Europe.

“We are suspending indefinitely new admissions of people into the transit zones,” said Gyorgy Bakondi, an adviser to nationalist Prime Minister Viktor Orban.

“We are seeing a certain link between the coronavirus and illegal immigrants,” he told a press conference.

Bakondi said that most migrants headed for Europe are Afghans, Palestinians, or Iranians, rather than Syrians, and many may have crossed Iran, a coronavirus hotspot.

Hungary has yet to record a confirmed case of coronavirus within the country.

Entry into the transit zones—container camps built into a fence along the Serbian border—will be halted “in the interests of protecting the 321 people waiting for decisions on their asylum applications who are already inside,” Bakondi said.

Only a trickle of asylum-seekers each week had been previously let into the camps, which have been harshly criticised by rights groups.

But the new measure “effectively shuts down access to asylum” said the Hungarian Helsinki Committee refugee rights NGO, as the camps are the only place people without valid visas have been able to file asylum applications since 2017.

Hungary’s move came after Ankara put pressure on Europe by opening its border for migrants to seek passage to the continent via Greece.

Greece said Sunday it has blocked nearly 10,000 migrants at its border with Turkey.

“Hungary will not open up or let through anyone,” Bakondi said, adding that police and military reinforcements will be sent to the border.

“The road does not lead here, it’s not worth trying this way,” he said.

Hungarian police said there has been a sharp rise in attempts to enter the country from the south, a border of the EU’s passport-free Schengen zone, since December.

Bakondi said around 7,000 attempts were made by illegal migrants to cross its borders so far this year, compared with only several hundred a month in 2019.