At least 34 people have been killed and 75 are wounded after a blast in the Turkish capital of Ankara.

Senior officials said the explosion was caused by a suicide car bomb.

A second official said gunfire was heard after the blast.

There was no immediate claim of responsibility for the attack.

On Friday, US officials warned of a possible imminent terror plot in the city.

It comes just weeks after 29 people were killed in a car bomb attack targeting the military in February.

The area, close to a courthouse and the Justice and InteriorMinistries, was crowded when the explosion happened at around 4.45pm GMT, state broadcaster TRT said.

They added a vehicle exploded at a major transport hub, hitting a bus carrying some 20 people near the central Guven Park and Kizilay Square.

The government has said the previous car bombing in Ankaraon February 17 was carried out by Kurdish militants.

Islamic State militants have meanwhile carried out at least four bomb attacks on Turkey since June 2015