ATHENS (Reuters) - A little-known anti-fascist group said on Saturday it was behind a bomb attack on an office of Greece's far-right Golden Dawn party this week that ripped through a wall and smashed windows but caused no injuries.

The dynamite-packed device was planted outside a branch of the party, whose popularity has surged during Greece's debt crisis.

The Anti-Fascist Front said in an Internet statement that it was behind Tuesday's pre-dawn attack near Athens. It said it was affiliated with the Informal Anarchist Federation (FAI), a group which has claimed several attacks across Europe, mostly in Italy.

"We decided to hit Golden Dawn's offices because we believe that you have to hit out at fascists first, before they hit you," the Front said.

The authenticity of its claim could not immediately be verified and a Greek police source said the group was not known to the security services.

Greek activists and politicians have called for the ultra-nationalist Golden Dawn to be banned. Its members have been seen giving Nazi-style salutes and its emblem resembles a swastika, but the party denies it is neo-Nazi.

Messages signed by the FAI were included in letter bombs sent last year to the Italian tax agency Equitalia, Germany's Deutsche Bank and the Greek embassy in Paris.

The Equitalia bomb blew off the finger of its director general.

People affiliated with the group also claimed responsibility for shooting and wounding an executive at Italian nuclear engineering firm Ansaldo Nucleare earlier this year.

(Reporting by Harry Papachristou; Editing by Tom Pfeiffer)