VIENNA (AFP) - Austrian armed commandos arrested on Friday (Jan 20) a man suspected of planning a "terrorist" attack in Vienna, police said, with authorities deploying additional officers and warning the public to be vigilant.

"In recent days indications have grown of an actual suspect planning a supposed act of terror, and Vienna police... immediately began investigating and implemented security measures," spokeswoman Irina Steier told AFP.

"The presence of uniformed and plainclothes police was increased and today at 6pm (1700 GMT) the suspect was arrested in Vienna near his home address on the basis of an arrest warrant," Steier said.

He gave no details of the suspect, except to confirm that it was a man and that investigations are continuing.

The Kronen-Zeitung published online a document from the interior ministry saying that a group of "radical Islamists of Albanian origin" intended to launch an attack in Vienna.

It said that according to information from a foreign intelligence agency and, independently from a foreign police force, the attack was to take place between Jan 15 and Jan 30.

The document added that a German-speaking sympathiser of the Islamic State in Iraq and Syria (ISIS) extremist group made explosives in Germany and that he intended to bring them to Vienna to carry out an attack.

He was not immediately able to complete his travel plans but the newspaper said that the suspect travelled from Germany to Austria on Friday.

"The man has been in custody... There are still lots of things to clear up," another police spokesman, Thomas Keiblinger, told the Austria Press Agency, declining to comment further.

Police also issued a public warning for people to be on the lookout at crowded public places and to inform police if they see any suspicious objects.

Interior Minister Wolfgang Sobotka was due to give a news conference at 8pm (1900 GMT) together with senior police officials, authorities said.

Austria has been spared the string of attacks by Islamists suffered by other European countries but has increased security measures.

In 2015, a record 90,000 people applied for asylum in Austria after hundreds of thousands of migrants transited the country bound for Germany and elsewhere.