A Chechen asylum seeker suspected of preparing to join Islamist guerrillas in Syria has been arrested in Austria, police said Tuesday, nearly two weeks after they detained nine others.

European countries have tightened controls over potential jihadists traveling to and from Syria and Iraq ever since Islamic State (IS) combatants overran large swaths of Iraq in June.

Nine people who had been given asylum in Austria have been arrested on suspicion of seeking to join the jihadist opposition in Syria, the government said on Wednesday.

The arrests follow an investigation by the Austrian secret service, said Interior Minister Johanna Mikl-Leitner, without giving any information on the identity of the suspects.

Austria's largest refugee center will no longer accept new arrivals from Wednesday due to massive overcrowding and political infighting over a recent influx of migrants.

Treatment in the center is "inhumane" and "unacceptable", said Erwin Proll, head of the regional government in Lower Austria where the center is located.

Iran will hold talks with world powers in Vienna this week aimed at resolving the Islamic republic's disputed nuclear program, an Iranian diplomat was quoted as saying Tuesday.

"The foreign ministers of the P5+1 (Britain, China, France, Russia and the United States plus Germany) will travel to Vienna this week, probably Friday, Saturday and Sunday, but that does not mean we have reached an agreement," the official IRNA news agency quoted the diplomat as saying.

Iran and world powers are yet to find common ground on the main issues in nuclear talks aimed at reaching a comprehensive agreement, Tehran's Foreign Minister Mohammad Javad Zarif said Friday.

His remarks, broadcast live on state television, came after five days of negotiations in Vienna that seek to transform an interim deal into a lasting accord to resolve a decade-long stand-off over Iran's nuclear ambitions.

As many as 10,000 people demonstrated in Vienna on Thursday in protest at a visit by Turkey's strongman Prime Minister Recep Tayyip Erdogan, organizers and police said.

Erdogan has been accused of autocratic tendencies in his home country and a similar trip to Germany last month ruffled feathers after he spoke out against assimilation of Turkish immigrants.

The United States and Iran briefly discussed the crisis in Iraq on the sidelines of a critical fifth round of nuclear talks in Vienna, U.S. officials said Monday

The two nations, which have been bitter foes for more than 30 years, are both deeply concerned by a major insurgency by Sunni militants who have overrun swathes of Iraq over the past week.

Austria warned Turkish Prime Minister Recep Tayyip Erdogan on Thursday not to say anything that may "split" Austrian society when he visits next week following a contentious visit to Germany.

The strongman leader ruffled feathers last month when he made disparaging remarks about a German opposition leader of Turkish origin and spoke out against "assimilation" in a speech in Cologne.

Austrian far-right leader Heinz-Christian Strache told Turkish Prime Minister Recep Tayyip Erdogan on Sunday to "stay at home," ahead of a controversial election rally planned in Vienna later this month.

"We don't need Erdogan in Vienna. I'll tell him right now: 'Erdogan, stay at home'," Freedom Party (FPOe) leader Strache told the daily Oesterreich.

A heavy explosion that almost flattened a Vienna apartment block was caused by the suicide attempt of a 19-year-old unemployed man, killed in the building collapse, Austrian police said Sunday.

A gas oven had been tampered with and the man was still clutching a cigarette lighter when he was pulled from the rubble on Saturday, police spokeswoman Adina Mircioane said.