Police stand outside the French embassy, where unidentified attackers threw an explosive device causing a small blast, in Athens, Greece, November 10, 2016. REUTERS/Alkis Konstantinidis

ATHENS (Reuters) - A Greek left-wing urban guerrilla group on Monday claimed responsibility for an attack with a hand grenade on the French embassy in Athens last week, which wounded one guard.

The attackers were riding a motorcycle when they threw the hand grenade outside the building opposite parliament, in one of Athens’s best-guarded areas. The attack occurred less than a week before a planned visit by U.S. President Barack Obama on Nov. 15-16.

In a statement uploaded on Athens Indymedia website, the Revolutionary Self-defense Group described the attack saying it was in protest at France’s foreign policy and its treatment of refugees.

The group has also claimed responsibility for an attack on the headquarters of the Socialist PASOK party in Athens in 2014 and an attack against the Mexican embassy in August.

“The political aim of the Revolutionary Self-defense Group in all three armed interventions was clear: attacking the state oligarchy, the dictatorship of the capital and its armed guards,” the group said, warning of more attacks against police.

Greek police were investigating the authenticity of the claim, one official said.

Small-scale attacks on businesses, police, politicians and embassies are frequent in Greece, which has a long history of political violence and is struggling to emerge from a huge debt crisis which has sent thousands to unemployment and cut incomes.

Police on Monday banned public gatherings in a large swathe of central Athens during Obama’s visit, excluding an area where protesters typically gather for demonstrations.