Turkish police on Wednesday arrested a former informant accused of instigating the 2007 murder of ethnic Armenian journalist Hrant Dink, local media reported.

Erhan Tuncel was arrested at an Istanbul villa and had been on the run since a court issued an arrest warrant against him last month, the private Dogan news agency reported.

Dink incurred the wrath of Turkish nationalists for calling the World War I massacre of Armenians a genocide, was shot dead in broad daylight in 2007 outside the offices of his bilingual weekly newspaper Agos.

The killing of the 52-year-old sent shock waves across Turkey and sparked accusations of state conspiracy after reports that security forces had known of the murder plot but failed to act.

The Star newspaper on Wednesday had published an interview with Tuncel in which the former informant said he was preparing his defence and was about to release names of other people involved in Dink's murder.

"I will reveal the names I am in contact with. The police forces have a big role in the Dink murder," Tuncel said in the interview, promising to surrender in two weeks.

A retrial of the high-profile case began on September 17 after an appeals court acknowledged that Dink's killers were part of a criminal conspiracy, overturning an original ruling that they acted alone.

An Istanbul court in 2011 had sentenced Dink's self-confessed killer Ogun Samast, who was tried separately as he was juvenile at the time, to 23 years in jail.

A year later, the court sentenced the so-called mastermind of the murder, Yasin Hayal, to life imprisonment for inciting the killing but acquitted 18 other defendants, ruling that there was no conspiracy.

In May, Turkey's appeals court partially overturned the 2012 verdict. It upheld the conviction for Hayal but ordered a retrial to look into whether he and another acquitted defendants belonged to a criminal network.