COLOMBO, (Reuters) - An opinion poll taken ahead of Sri Lanka’s general election in December shows more support for the country’s main opposition party, but many voters remain undecided, a local newspaper said on Sunday.

The poll showed an alliance led by the opposition United National Party receiving 40 percent of votes at the December 5 election compared to 33 percent for the ruling Peoples’ Alliance coalition, the independent Sunday Times newspaper said.

But around 11 percent remained undecided suggesting the result of the election could swing either way.

The results also showed a 13-percent support base for a radical Marxist party that recently supported the government suggesting it could increase its number of seats in the 225-seat legislature from the current 10 seats.

Sri Lanka’ president Chandrika Kumaratunga in October called for a snap election, just one year after the previous election, after her ruling coalition lost a majority in parliament and looked set to lose a no-confidence motion.

The last general election produced a hung parliament and the president had to cobble together a majority with the support of a small Muslim party and subsequently with the radical Marxist People’s Liberation Front.

The opinion poll was conducted by Survey Research Lanka (pvt) Ltd last month in all parts of the country except the war-torn north and east where the government is waging an 18-year war against separatist rebels.

Lawmakers are elected through a complicated mix of proportional representation and direct voting in Sri Lanka’s electoral system.