At least 20 people were killed Saturday in a huge explosion close to the main train station in Turkey's capital Ankara ahead of a peace rally, media reports said.

Eyewitnesses told AFP several corpses were seen lying on the ground while NTV television and the Dogan news agency said at least 20 people were killed. Some 100 people were wounded, NTV added.

The area was to have hosted an anti-government peace rally organised by leftist groups later in the day, including the pro-Kurdish Peoples' Democratic Party (HDP).