LONDON (AFP) - The Labour Party lost a key by-election in the Scottish constituency of Glasgow East, according to results announced Friday.

John Mason of the Scottish National Party (SNP) defeated Labour's Margaret Curran by a margin of 11,277 votes to 10,912 votes, reversing a Labour majority of more than 13,000 votes.

Earlier in the day, Labour had requested a recount, which delayed the result being announced by around an hour.

The SNP saw its vote share in Glasgow East, Labour's third-safest seat in Scotland, rise by 26 percent compared to the last general election in May 2005, while Labour's dropped by 19 percent.

Turnout was around 42 percent, compared to 48 percent in the last general election.

The defeat deals a fresh blow to Prime Minister Gordon Brown and to Labour, which in recent months had already lost two other by-elections and hit record lows in opinion polls, with Brown also under pressure because of the rising cost of living, his administration's recent economic record and his own leadership style.