Britons are likely to face an unusually long wait to learn the outcome of what is expected to be the closest parliamentary election in almost two decades.

Forty-two of the 650 seats plan to delay the counting of votes until the morning after polls close, the Electoral Commission watchdog said Wednesday. Officials in a further 69 seats have yet to decide when to start counting ballots.

The election will be held Thursday, May 6 and polls close at 10 p.m. It is a tradition of British political life for the counts to start at town halls across the country within minutes of voting ending and there is an unofficial race for the honour of being the first seat to declare a result.

However, officials in some areas have decided to delay the count to save costs and to comply with stricter rules on postal ballots where dates of birth and signatures will be checked.

Justice Secretary Jack Straw has introduced a clause in a bill going through parliament which would force officials to start the count within four hours of polls closing. However, it is unclear if that bill will be passed before parliament is dissolved Monday.

Opinion polls show the Conservatives ahead of Labour but by an insufficient margin to guarantee an outright majority in parliament.

Financial markets are nervous about an inconclusive election which they fear could lead to policy paralysis and hamper efforts to tackle a record budget deficit.

Exit polls Thursday night will give the first indication of the election outcome, but a close contest could be settled by the results in a few marginal constituencies where the main parties enjoy similar levels of support.