A man has appeared in court charged with possession of a machine gun and mustard gas canisters and with discharging mustard gas into fresh inland waters.

Martyn Tasker, 39, appeared before Lincoln magistrates along with Michaela Tasker, 31, and Stuart Holmes, 50.

The three were arrested after the discovery of containers filled with mustard gas, a highly noxious substance, in woodland in Lincolnshire in October 2017. Army bomb disposal units were called in at the time to remove 150 canisters from Roughton Woods and Stixwould Lake.

Martyn Tasker was charged with having a working Bren machine gun and possession of mustard gas canisters, and with discharging mustard gas into fresh inland waters.

Michaela Tasker was charged with possession of mustard gas canisters and discharging mustard gas into fresh inland waters.

Holmes was charged with possession of mustard gas canisters, depositing mustard gas in Roughton Woods, Lincolnshire, depositing mustard gas in a manner likely to cause pollution of the environment or harm to human health, and discharging mustard gas into fresh inland waters.

During a short hearing before Lincoln magistrates on Thursday, the three accused confirmed their names, addresses and dates of birth and were not required to enter a plea. They were granted unconditional bail to appear at Lincoln crown court on 12 September.

The court heard that the charges had been brought jointly by the Crown Prosecution Service and the Environment Agency.

Police declared a major incident after the canisters were first discovered on the former second world war RAF base at Roughton Woods, near Woodhall Spa.

Bomb disposal officers were called in and testing of the substance was carried out at the government’s Porton Down military research laboratory.

Two people who found the canisters needed hospital treatment for burns and respiratory problems but were able to go home shortly afterwards.

The highly dangerous gas, a chemical warfare agent used during the first world war, causes severe irritation to the skin, eyes and lungs.

RAF Woodhall Spa, a satellite of the main RAF Coningsby site, was shut down in the mid 1960s.