Tata Motors-0.73 % faces the maximum fine of Rs 1,346 crore, followed by Maruti Suzuki Rs 471 crore, Mahindra & Mahindra Rs 292 crore, General Motors Rs 85 crore, Honda Car India Rs 78 crore.

Reacting to the news, Tata Motors slipped as much as 2.1 per cent followed by M&M which dropped 1.23 per cent and Maruti Suzuki was down 1.19 per cent in trade today.

At 09:30 a.m.; Tata Motors was trading 1.4 per cent lower at Rs 500.95, Maruti Suzuki was down 0.56 per cent to Rs 2786.65 and M&M was trading 0.9 per cent lower at Rs 1393.45.

The decision, spelt out in a 215-page order, says that auto companies indulged in anti-competitive practices as they did not make genuine spare parts freely available in the open market, upholding the contentions of a petition filed by a complainant in 2011, ET reported.

The fine has been calculated at 2% of average turnover, added the report.

Honda Siel 1.60 %, Volkswagen India, Fiat India, BMW India, Ford India, General Motors, Hindustan Motors, Mercedes - Benz, Nissan Motors, Skoda Auto India and Toyota Kirloskar are the other companies on whom fines have been slapped.