Seized last Friday, the explosives and the suspects were found in a car stopped by police.

The following day police found a similar amount of the same type of explosive and arrested two presumed Kurdish separatists at the other end of the country in a suburb of Izmir.

A series of bombings in recent months has been attributed by Turkish authorities to Kurdish militants. The most deadly killed five people last summer, including a British man and an Irish adolescent.

Some 37,000 people have been killed since 1984 when the rebels first took up arms for self-rule in mainly Kurdish southeast Turkey.