COLOMBO, Dec 4 (Reuters) - The following are key facts about Sri Lanka’s parliamentary elections on December 5:

PARLIAMENT

The single chamber has 225 seats of which 196 are elected through a complicated mix of proportional representation and direct voting from each of the country’s 22 electoral districts. The other 29 are allocated to parties on the basis of the number of votes they receive at the national level.

Parliament normally sits for six years.

ELECTORAL SYSTEM

Voters in each of the 22 electoral districts must first vote for a political party or independent group, and then cast three so-called preference votes for candidates from the same party or group.

The seats are allocated among parties in proportion to the number of votes they receive in each district. The candidates with the highest number of preference votes from each party enter parliament according to the number of seats won by the party in the district.

The number of votes it takes to win a seat depends entirely on voter turn-out in each district.

The number of seats elected by each district varies from 22 in the capital Colombo to five in several smaller districts.

ELECTORATE

Slightly more than 12 million people are registered to vote, including about 200,000 postal voters.

CANDIDATES

There are 5,048 candidates from 29 registered parties and dozens of independent groups. Election laws require the parties to field a specific number of candidates for each district. The People’s Alliance is contesting all 22 districts together with its regional allies and the United National Party is contesting the same districts on its own. Most of the other groups are not fielding candidates in all districts.

VOTING

Polls open at 7 a.m. and close at 4 p.m. (0100 to 1000 GMT) on December 5 at nearly 10,000 stations across most of the country. There will be no polling centres in parts of the country’s north which are controlled by the separatist Liberation Tigers of Tamil Eelam rebels.

Instead, polling centres for voters from these areas will be set up in government-held territory.

Absentee voting was completed in the two weeks before the poll, but these ballots will be counted only after all votes have been cast.

VOTE COUNTING

Vote counting at 810 counting centres will begin as soon as all the ballot boxes arrive at the counting centres in each district. The Elections Secretariat will start announcing interim results late on Wednesday, but final official results will not be known until Thursday.