State-run Coal India has said that it will incur an additional burden to the tune of Rs 6,500 crore a year due to a 25% increase in workers' wages under the new pact.

"The additional financial impact due to signing of National Coal Wage Agreement - IX on Coal India Ltd would be Rs 6,500 crore per annum," the world's largest coal miner said in a filing to the BSE.

It signed a pact with its subsidiaries and representatives of central trade unions -- INTUC, AITUC, HMS and CITU to increase wages by 25% on January 31.

The hike will benefit over 370,000 workers of the firm.

"Minimum guaranteed benefit shall be 25% in the total emolument as on June 30, 2011 ... Minimum basic enhanced from Rs 8,360 per month to Rs 15,712.62 per month with effect from July 1, 2011," the company informed BSE.

At present, Coal India and its subsidiaries spend about Rs 20,000 crore annually on salaries of workers which is roughly over 40% of the cost of production.

As per the new pact, the house rent allowance in non-urban areas would be two per cent of basic per month instead of fixed amount of Rs 150 a month, he said.

Earlier this month, the company posted a 54% rise in consolidated net profit at Rs 4,037.7 crore for the quarter ended December 31, on the back of improved sales.

The company had reported a consolidated net profit of Rs 2,621.5 crore in the October-December quarter of 2010-11. The consolidated total income rose to Rs 17,205.1 crore from Rs 13,937.4 crore for the quarter ended December 31, 2010.

Coal India CMD Zohra Chatterji had said that the company will make every effort to take the PSU to further heights including increase in production.