Police in Turkey say they have arrested a "key suspect" in last month's suicide bomb attacks in Istanbul.
The suspect was arrested as he was about to cross to Iran
They believe the Turkish man - identified only by his initials F Y - helped prepare the explosives and trucks used in the four attacks.
Two synagogues, the British consulate, and offices of the HSBC bank were hit.
The authorities say the man was arrested on Wednesday in south-eastern Turkey while trying to flee to Iran with a forged passport.
Early on Sunday, the suspect was taken by the police to an industrial district of Istanbul and questioned at a workshop where he and others allegedly made the explosives.
He was taken to the site in an armoured vehicle escorted
by a convoy of police cars.
Eyewitnesses said he appeared to be about 30 years old, and had a short beard and dark hair. He wore a brown jacket and grey trousers.
News of the man's arrest came as the death toll in the four attacks
rose to 62, including the four suicide bombers. A 31-year-old man died from injuries
received in the bombing at the HSBC bank, Anatolia news agency reported.
Police said the suspect was expected to be charged later on Sunday.
About 30 people have so far been charged in connection with the attacks on two separate dates last month in Istanbul.
Most of those killed in the four bombings were Turkish.
On 15 November, two car bombs went off within minutes of each other at synagogues in the districts of Beyoglu and Sisli.
On 20 November, an explosives-laden van blew up outside the HSBC bank building, devastating its facade.
Minutes later, another van crashed through the gates of the British consulate and blew up. The British consul general, Roger Short, was among the dead.
Turkish officials have said the bombers were Turkish nationals with links to radical Islamic groups.