Bangalore, Aug 21 - The ruling Bharatiya Janata Party (BJP) and the main opposition Congress suffered huge blows in Karnataka Friday with state minister V. Somanna and union Labour and Employment Minister Mallikarjun Kharge's son Priyank losing assembly by-polls held Aug 18.

Somanna, the religious endowment and housing minister, was defeated by Congress novice Priya Krishna in Govindarajnagar in western Bangalore by 5,239 votes, the state election authorities announced.

Somanna had won the seat as a Congress candidate in May 2008 assembly polls but quit the seat and the party to join the BJP ahead of this year's Lok Sabha elections. He was rewarded with a ministership.

Hence Govindarajnagar had become a prestige battle for Chief Minister B.S. Yeddyurappa, who has received flak from his party members for wooing opposition legislators with promise of plum posts.

Another Congress defector to the BJP to be defeated was C.P. Yogeshwar, a Kannada film actor and realtor. He lost to M.C. Ashwath of the Janata Dal-Secular (JD-S) in Channapatna, 60 km from here.

The BJP, however, scored a big win when its candidate Valmiki Naik defeated Kharge's son Priyank, contesting an election for the first time, by 1,606 votes in Chittapur (Scheduled Caste) constituency in Gulbarga in north Karnataka, about 600 km from here.

Kharge had vacated the Chittapur seat on his election to the Lok Sabha.