Thai Prime Minister Abhisit Vejjajiva received a boost from weekend by-elections, increasing his parliamentary majority by 11 seats to 48, election officials said on Monday.

The Election Commission said Abhisit's coalition, led by his Democrat party, picked up 20 seats in Sunday's run-off. The opposition Puea Thai party and its allies only gained nine seats.

The by-elections were to replace 29 MPs banned from politics for five years by a Dec. 2 court ruling that dissolved the previous People Power Party-led (PPP) administration for vote fraud.

The results were broadly in line with expectations, although analysts had expected Puea Thai, the PPP's substitute, to fare slightly better and gain 11 seats.

Speaking earlier to reporters, Abhisit urged all members of parliament to focus on efforts to revive an economy teetering on the brink of recession.

"We want the conflicts to end and to give the government a chance to work and fix the economy quickly," he said.

Even though the parliamentary numbers now look slightly stronger for Abhisit, analysts said the results could weaken his hand within the coalition since the gains were notched up by allies of his Democrat party.

"There are two margins here -- the margin of the coalition over the opposition, and the margin within the coalition," said Thitinan Pongsudhirak of Bangkok's Chulalongkorn University.

"The less margin the Democrats have within the coalition, the less leverage they have. That is important when they have no-confidence debates," he said.

Abhisit's key coalition partner is Newin Chidchob, an up-country political wheeler-dealer banned from politics after the 2006 coup against Thaksin Shinawatra.

Newin was one of Thaksin's closest allies, but his "Friends of Newin" faction split from the pro-Thaksin Puea Thai late last year to ally with the Democrats and allow them to break months of political stalemate.

However, the alliance exposed Abhisit to criticism of pandering to Thailand's traditional money politics.

In a separate election for Bangkok governor, Democrat candidate Sukhumbhand Paribatra, a former foreign ministry official, scored an overwhelming victory.