An armed militant Kurdish group has claimed responsibility for an explosion in Turkey's commercial capital, Istanbul, that injured 14 people. The group known as the Kurdistan Freedom Falcons told the Netherlands-based Firat News Agency it had carried out the attack to protest the detention conditions of the Kurdish rebel leader Abdullah Ocalan.

The blast took place in an internet café frequented by police in Istanbul's Bayrampasa district. Police officers were reportedly among the injured. The Freedom Falcons have been blamed for a series of attacks against civilians in Turkey last year, including a blast on board a minibus in the Aegean coastal resort of Kusadasi. Two foreign tourists were killed in that attack.

The Falcons are believed to be the guerrilla arm of the outlawed Kurdistan Workers' Party that has been fighting for Kurdish autonomy in the country's predominantly Kurdish southeast region since 1984. The group, known as PKK for short, declared a unilateral ceasefire in 1999 following the capture of its leader Abdullah Ocalan. The PKK resumed its armed campaign last year saying the Turkish state had failed to respond to its overtures and had continued its offensive against the rebels.

Ocalan has been held in solitary confinement in an island prison off the coast of Istanbul since he was sentenced to death by a Turkish court on treason charges in 1999. That sentence was later commuted to lifetime imprisonment when Turkey abolished the death penalty in 2003 as part of a reform package aimed at winning membership of the European Union.

Ocalan's lawyers have expressed concern about his health in recent days saying they have not been allowed access to their client. In a statement the Justice Ministry denied claims that Ocalan had suffered a heart attack earlier this week, saying he was in good health.