"Our acts are a stand against the annihilation system against the Kurdish people," said a statement posted on the website of the Kurdistan Freedom Falcons (TAK).

"Our acts of reprisal will intensify and diversify as long the shadow of death remains on the people of Kurdistan," it added.

Four people were slightly injured in Thursday's attack when a time bomb placed in a garbage container went off near a bus stop in the crowded business and tourist district of Eminonu.

Turkish officials say TAK is a front which the separatist Kurdistan Workers' Party (PKK) uses for its attacks on civilian targets while the PKK claims TAK is a splinter group over which it has no control.

TAK has acknowledged responsibility for several deadly bomb attacks in urban centers across Turkey since last year.

More than 37,000 people have been killed since 1984 when the PKK, blacklisted by Turkey, the United States and the European Union, took up arms for self-rule in the country's mainly Kurdish southeast.

Tension has escalated in the southeast since June 2004 when the group called off a unilateral ceasefire.