Two men accused of planning an extremist attack on a Jewish restaurant in central Athens and possibly other targets that would produce mass civilian casualties have been arrested on terrorism charges in Greece, police said on Tuesday.

The suspects were charged with membership of a terrorist organisation and were being held at police headquarters in the Greek capital, authorities said.

A third man, who is not in Greece, was wanted for questioning and charged in absentia.

Government and police officials told the Associated Press that both suspects were of Pakistani origin. The officials asked not to be identified pending official announcements.

The two suspects both entered Greece illegally from neighbouring Turkey and have been in the country for at least four months.

As part of their investigation, police searched multiple sites in Athens as well as in southern Greece and on the island of Zakynthos.

The arrests were made because the attack at the Jewish restaurant was believed to be imminent, the police and government officials said.

The two men in custody are believed to be part of an overseas network and are scheduled to be questioned by a public prosecutor Friday, the officials said.

“Their aim was not only to cause the loss of life of innocent citizens, but also to undermine the sense of security in the country, while hurting public institutions and threatening (Greece’s) international relations,” a police statement said.

Greece’s anti-terrorism police division and national intelligence service were involved in the arrests, and received assistance from a foreign intelligence service that was not identified, according to the statement.

“The operation demonstrates that the country’s security authorities maintain a high state of readiness for all Greeks and all visitors to our country,” public order minister Takis Theodorikakos said in a tweet.