COLOMBO (Reuters) - Sri Lanka's ruling United National Party (UNP) has won decisive gains in a general election, final results showed on Tuesday, putting it in a position to form a stable government after eight months of minority rule.

Prime Minister Ranil Wickremesinghe's centre-right party won 106 seats, seven short of a clear majority, election officials said.

Still, he should be able to control Parliament with the support of allies of President Maithripala Sirisena.

That was ahead of the 95 seats won by the opposition alliance led by former president Mahinda Rajapakse, whose attempt to stage a comeback came up short.