Residents of the Scottish town of Lockerbie are commemorating the 20th anniversary of the bombing of a US-bound aircraft over the town in which 270 people died.

Memorial services are being held in the 4,000-strong community from on Sunday, to remember those killed in the blast and its aftermath.

The explosion killed 259 passengers and crew, most of them Americans, while 11 people were killed in the town as debris from the stricken aircraft fell on houses.

Relatives of those killed on the aircraft are set to attend a service at London's Heathrow Airport on Sunday, where Pan Am flight 103 departed on the evening of December 21, 1988.