Two technical trainers -- a South African and an UK-based Indian -- were rescued while four miners were killed after a roof collapsed in a coal mine under the state-owned Singareni Collieries Company Limited at Kothagudem in Khammam district in Andhra Pradesh on Sunday.

Company officials said on Sunday night, "The South African technician Thomas N Kosi [Images] was rescued at 6 pm, almost seven hours after the incident while a UK-based Indian technician Pratap Kumar Sharma was brought to the surface at 3.30 pm. Both of them suffered leg injuries and were admitted to the SCCL hospital at Kothagudem."

Kosi, a shuttle car operator, and Sharma, operator, were working for the London-based Joy Mining Machinery Company, the supplier of 'continuous miner machine' which mechanically extracts coal without any human intervention.

The system was introduced in the SCCL in August 2006. The two trainers of company were training the SCCL miners about the technology.

The roof fall occurred around 9 am on Sunday when the continuous miner machine was about to resume its operations in the day.

Six persons-- four SCCL miners and the two technicians of the British company -- were inside the seventh incline of the underground mine.

They went 500 mt down in a lift to take up digging in the 72nd junction area where a three-metre deep coal seam was identified. A huge chunk of the roof weighing 50 tonnes came crashing down, sealing their exit.

No regular miner was on duty at the time of the accident as it was a weekly off for the 1,600 coal workers of Venkatesh Khani, one of the oldest mines under the SCCL.

The mine, started in 1954, has an annual production capacity of 450,000 tonnes. The continuous miner machine, with a daily production capacity of 1,000 tonnes, was introduced in the mine on September 4.

As the roof caved in, four miners -- under manager T Sudhir Babu, head overman N Ramji (47) and general workers Podu Butchaiah (38) and K Ramachander (37) -- died on the spot, while two technicians -- Kosi and Sharma -- sustained severe injuries.

Rescue teams and other miners immediately rushed to the spot and took up rescue operations to reach the workers trapped in the debris about 1.1 km away from the pithead.

It took four hours for them to clear the way. The bodies of Sudhir Babu and Ramachander were brought to the surface at around 4 pm.

Safety department officials and directors of the company monitored the salvage operations. Efforts were on to retrieve the bodies of two other workers -- Ramji and Butchaiah.

Singareni collieries chairman and managing director S Narsinga Rao, Khammam District Collector Sashibhushan Kumar, Superintendent of Police Rajiv Kumar Meena, Union Minister of State for Women and Child Development and Member of Parliament from Khammam Renuka Chowdhary and Kothagudem legislator Vanama Venkateswara Rao visited the mine.

The company officials announced that ex-gratia would be paid to the families of the deceased miners as per the norms.