Austrian police have arrested three youngsters, including a 14-year-old, for allegedly planning an attack at Vienna's pride parade, which drew hundreds of thousands of people, officials said Sunday.

The men aged 14, 17 and 20 and suspected of being Islamic State (IS) sympathisers were held ahead of the parade, according to domestic intelligence agency (DSN) chief Omar Haijawi-Pirchner.

He told reporters that there was "never any threat" to those who participated in the Pride Parade in central Vienna on Saturday. 

"They sympathised with the Islamic State online and shared extremist content. In this context, the suspects focused on the Pride Parade as a potential target for an attack," the interior ministry said in a press release.

During raids on two premises on Saturday, authorities discovered weapons and other evidence against the three Austrians with Bosnian and Chechen roots.

One of them was already previously known to police. They had planned to use "knives or vehicles" in the attack, police told reporters.

Some 300,000 took part in the parade for LGBTQ rights.

In November 2020, a convicted Islamic State group sympathiser went on a shooting rampage in downtown Vienna, killing four and wounding 23 others before police shot him dead.

It marked the Alpine nation's first deadly jihadist attack.

Earlier this year, a Vienna court sentenced two alleged accomplices of the gunman to life in prison, while two others received prison terms of 19 and 20 years.

jza/cw