A secret airstrip is being built near a diamond field under the Zimbabwean army's control, the Daily Telegraph reported.

The Chiadzwa diamond field was illegally seized by the military 14 months ago. According to human rights groups, hundreds of miners were killed when soldiers seized the area in November 2008. It is believed that the mile-long runway is intended for weapon shipments, probably from China – which has long been Zimbabwe's main source of arms – for which the troops would pay with gemstones from the Chiadzwa diamond mines.

Aerial photos show construction is underway, with a newly built control tower apparently complete and the runway nearly ready for surfacing.

The mining area has several other airfields within close proximity, and so there is no obvious need for an additional runway so close to the diamond field. A Western diplomat told the Daily Telegraph that the existence of the runway was "extremely" worrying.

The Zimbabwean Military's presence on the diamond field is in direct violation of Zimbabwe court orders obliging compliance with Kimberley Process directives.

Nevertheless, construction of the new runway suggests that the military now wants to use its access to rough diamonds – local production is estimated at £125 million a month – to obtain weapons from overseas suppliers.

The discovery of the airstrip comes at a highly sensitive time for Zimbabwe, as the future of its joint government, led by the President Mugabe's Zanu-PF party and the Movement for Democratic Change (MDC), hangs in the balance.