New Delhi, April 30 -- BENGALURU, April 30 (Reuters) - India has slashed Vodafone Idea's long-pending dues to 640.46 billion rupees ($6.75 billion) from 876.95 billion rupees earlier, the telecom firm said on Thursday.

The dues stem from a long legal dispute over government's method of calculating the so-called adjusted gross revenue, which telecom operators had contested as this metric determines licence fees and other dues.

In December, the government approved a partial moratorium on Vodafone Idea's dues, freezing them at 876.95 billion rupees and deferring repayments to the 2030s, providing near-term cash flow relief for the debt-saddled firm.

Now, the telecom company will have to pay 1 billion rupees annually over four years from f...