Vienna police say they expect protests against Israel's participation in the Eurovision Song Contest to include "blockades and disruption attempts," calling the competition in the Austrian capital one of the biggest security events they have faced.

A celebration of pop music and high camp, the contest is taking place in particularly tense circumstances this year as five countries' broadcasters including Spanish heavyweight RTVE and Ireland's RTE, are boycotting over Israel's conduct of the war in the Gaza Strip, launched in retaliation for the October 2023 attacks on Israel by Hamas.

The Iran war has since exacerbated that tension.

A handful of demonstrations, mainly against but also in favour of Israel's taking part, have been registered so far for next week, with attendance estimated at up to 3000.

Protests must be registered with 48 hours' notice.

"We expect there will in fact be blockades and disruptive actions, particularly on the day of the final, whether through authorised or unauthorised gatherings," Xenia Zauner, a senior police official who will oversee the security operation, told a press conference.

Demonstrations against Israel's participation have become a feature of recent editions of the contest.

The eve of the final - Friday, May 15 - is also Nakba Day, when Palestinians commemorate the loss of their land after the 1948 war at the birth of the state of Israel.

The word "nakba" means "catastrophe".

Zauner said that day has "great emotional significance for the pro-Palestine movement".

Police are preparing for a wide range of threats.

Drones will be banned within 1.5km of sites including the contest venue, and the US Federal Bureau of Investigation will set up a task force in New York next week that Austrian authorities can contact around the clock to address cyber threats, police said.

While the general "terrorism alert level" in Austria has been at the second-highest notch for more than two years, there is no specific threat against the contest, Vienna police Vice President Dieter Csefan said.

Those attending the event should expect international airport-level security screenings, and can only bring small transparent bags inside, police said.

Airport-style security will also be set up at a large fan area in front of city hall, they added.