Sweden's left-wing opposition parties have more than an eight-percentage-point lead over the centre-right government ahead of September's general election, a poll published Friday showed.

• Swedish politicians fishing for votes in London

The Synovate survey, published in the Dagens Nyheter daily, indicated the three-party opposition enjoyed 51.2 percent voter support, compared with 43.1 percent for the four-party ruling coalition.

The latest poll hinted that the opposition bloc was strengthening its lead, after a Synovate study last month gave it an advantage of just 4.6 percentage points over the government.

On an individual party level, the main opposition Social Democrats remain Sweden's most popular party, with 35.1-percent voter support, according to Friday's poll, while Prime Minister Fredrik Reinfeldt's Moderate Party drew 28.8 percent backing.

The Moderate Party was the only one in the governing bloc to inch up slightly from its position in the 2006 elections.

The three other ruling parties had seen support shrink dramatically, with the Christian Democrats falling in the poll below the four-percent mark needed to enter parliament.

Just a year ago, several opinion polls showed a clear lead for the governing alliance, which garnered approval ratings of up to 50 percent.

The government had won widespread approval for its handling of the financial crisis and Sweden's rapid recovery, but has since been damaged by a series of controversies, including a dramatic cut in the numbers of those eligible for long-term sick leave compensation.

According to Synovate, the opposition's showing in Friday's poll is mainly due to a stronger mobilisation of left-wing voters, while an increasing number of traditional centre-left voters were expressing uncertainty about who they would cast their ballots for.

"If both blocks had the same level of mobilisation the distance between them would shrink by a few percentage points," Synovate analyst Nicklas Kaellebring told Dagens Nyheter.

Friday's poll also showed support for the far-right Sweden Democrats, which is not part of either bloc, with four percent of those questioned saying they would vote for the party.

If the party, which won 2.9 percent of the vote in 2006, achieves a similar result in the September 19 poll, it would win its first seat in parliament.

For Friday's poll, Synovate surveyed 2,677 people between April 12-28.