Shares of Hindalco Industries tumbled over 5 per cent today after its promoter Kumar Mangalam Birla was summoned as accused by a special court in coal scam case.

The stock plunged 5.1 per cent to Rs 131 on the BSE. On the NSE, the shares slipped 5.28 per cent to Rs 130.75.

The stock was the biggest loser among the blue-chips on both Sensex and Nifty.

Former Prime Minister Manmohan Singh, industrialist Kumar Mangalam Birla, ex-coal secretary P C Parakh and three others were today summoned as accused by a special court in a coal scam case pertaining to the allocation of Talabira-II coal block in Odisha in 2005 and asked to appear before it on April 8.

The court has also summoned Hindalco, its officials Shubhendu Amitabh and D Bhattacharya as accused in the case.

The case pertains to the allocation of Talabira-II coal block in Odisha to Hindalco in 2005, when the then Prime Minister Singh was holding the coal portfolio.