ISTANBUL (REUTERS) - Turkish Prime Minister Tayyip Erdogan's ruling party has seen its popularity slip since a corruption scandal erupted last month but remains comfortably ahead of the main opposition, the first major poll published since the affair showed on Thursday.

The survey by Sonar research, one of Turkey's main pollsters, put support for the AK Party at 42.3 per cent, two percentage points below its previous poll last August and well below the 50 per cent the party won at the last election in 2011.

The main opposition CHP scored 29.8 per cent in the poll, its highest since June 2011 according to Sonar, whose surveys tend to put ruling party support below the AKP's own estimates.

The corruption scandal, which erupted in mid-December with the detention of prominent businessmen close to Mr Erdogan and three ministers' sons, poses arguably the biggest challenge to the ruling party since it came to power more than a decade ago.

The government has said neither street protests last summer nor the corruption scandal have had a major impact on AKP popularity. Deputy Prime Minister Bulent Arinc said last week the party enjoyed support of around 52 per cent, based on four surveys commissioned by the government.