Austria's foreign ministry has been targeted by "serious cyber attack", officials said, warning another country could be responsible.

The attack, which began yesterday, was continuing today and "experts say it could last several days," a foreign ministry spokesman said.

"Due to the gravity and nature of the attack, it cannot be excluded that it is a targeted attack by a state actor," a statement said.

"In the past, other European countries have been the target of similar attacks.

Immediate measures have been taken and a "coordination committee" set up, the statement said.

The attack came as Austria's Greens gave the go-ahead to a coalition with the country's conservatives at a party congress in Salzburg, removing the last obstacle to the unprecedented alliance.

The German government's IT network was hit by a cyber attack in 2018.

Last year the EU adopted powers to punish those outside the bloc who launch cyber attacks that cripple hospitals and banks, sway elections and steal company secrets or funds.