ISTANBUL: A banned radical Turkish Marxist group has retracted its claim for a suicide bombing in the heart of Istanbul's tourist district, saying it did not carry out the attack that killed the bomber and one policeman.

Examine: Radical Marxist group claims Istanbul suicide attack

Reports earlier this week suggested Tuesday's attack was carried out by a Russian woman from the Muslim Caucasus region of Dagestan, and not the female bomber that the far-left militant group initially said had executed the strike.

“The attack on January 6 in Sultanahmet... was not carried out by our organisation,” the Marxist Revolutionary People's Liberation Party-Front (DHKP-C) said in a statement on its website.

“We therefore withdraw our claim for the action. We apologise to our people and our supporters,” it said.

Take a look: Female suicide bomber hits police station in Istanbul

It said that the error was down to a “technical problem” that had arisen due to the need to keep internal communications to a minimum while living under “fascist conditions”.

Without giving further details, the group said that it had been preparing an action which would have coincided with the Sultanahmet attack.

Doubts were first raised when the mother of the suicide bomber named by the DHKP-C — Elif Sultan Kalsen — was taken to identify the corpse and said it was not her daughter.

Turkish private news agency DHA, without giving its sources, then said the bomber had been named as Russian citizen Diana Ramazanova (initially given as Ramazova) from the Russian region of Dagestan.

Turkish Interior Minister Efkan Ala announced early Thursday that the “identity (of the bomber) had been determined” but officials have so far refused to disclose the name.

An autopsy had also determined that she was two months pregnant, reports said. The fate of Elif Sultan Kalsen remains unclear.

The statement that the bombing was not carried out by the DHKP-C raises new and potentially troubling questions about who was behind the attack.

Ramazanova is now being investigated for any links to Al Qaeda and the Islamic State (IS) militant group, Turkish media reports have said. She had entered Turkey as a tourist seven months ago.

Security has been high in Turkey over the past few months, amid fears of attacks by Kurdish militants and jihadists who have attacked swathes of Iraq and Syria.