(Updates with analyst comment, details) COLOMBO, Jan 28 (Reuters) - Two dozen opposition MPs defected to Sri Lanka's minority government on Sunday with some securing posts as ministers in a reshuffled cabinet, a senior presidential aide said. But the defections left the government just shy of a parliamentary majority seen key to political stability amid a new chapter in a two-decade civil war with Tamil Tiger rebels, and could also derail a cross-party push to find a political solution to the conflict. "Eighteen UNPers have crossed over and 10 (UNP) newcomers are in the cabinet," Lucien Rajakarunanayake, head of the president's research and information unit, told Reuters referring to the main opposition United National Party (UNP). Six members of the Sri Lanka Muslim Congress, the island's main Muslim party, also joined the government. Analysts warned that the UNP cross-overs had effectively ruptured the opposition party at a time when it was working with the government to build consensus on how to end a war that many fear is set to escalate. Both parties agreed a pact last year to work together to help end a conflict that has killed more than 67,000 civilians, troops and rebel fighters since 1983 -- and around 4,000 people in the last year alone. "The (pact) between the government and the UNP is effectively defunct with the crossing over," said Paikiasothy Saravanamuttu of independent think-tank the Centre for Policy Alternatives. "The tragedy of this whole thing is that apart from the promise of (the pact) being lost, we also don't have a strong opposition in the country ... That's not healthy in parliamentary democracy." Five high profile UNP MPs had already defected to the government since President Mahinda Rajapakse took power in late 2005, further distancing the bickering parties. If the government can secure one more seat to win a simple majority, it will also mean Rajapakse will not be hostage to volatile, hardline Marxist and Buddhist monk allies who have repeatedly conditioned support for the government and are against a political deal with the Tigers. However to the consternation of observers, the government -- apparently emboldened by the capture of a key eastern rebel stronghold -- has vowed to wipe out the Tigers' military machine altogether, paving the way for more bloody war. Analysts say the government is underestimating the rebels, and see no clear winner.
