Sweden's centre-right coalition edges ahead in polls after the "red-green" presented plans to hike taxes and increase benefits.

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Sweden's ruling centre-right coalition has edged in front of the left-wing opposition in voter intentions ahead of the September election, a poll published Thursday showed.

Thursday's Demoskop survey was the first in recent weeks to show the four-party coalition ahead of the opposition, which is made up of the Social Democrat, Green and Left parties.

The government's 49.2 percent voter support was however less than 2.0 percentage points ahead of the opposition, which garnered 47.4 percent of voter support.

The poll was also the first to be published since the opposition parties, which are presenting themselves as a united "red-green" coalition, presented a shadow budget staking out higher taxes -- including on alcohol, tobacco, and petrol -- as well as increased benefits and job-creation measures as the main priorities of their campaign.

"We checked the results before and after the red-green shadow budget presentation. Before, there was a constant lead for the opposition, but after there was a shift in conditions," Demoskop's head Anders Lindholm told the Expressen daily, which published the poll.

In the last Demoskop poll, published on April 12, the opposition had an eight percentage point lead over the government.

Thursday's poll showed that on an individual party level, the main opposition Social Democrats remains Sweden's most popular party, with 33.8-percent voter support, while Prime Minister Fredrik Reinfeldt's Moderate Party drew 30.6 percent backing.

The Green party, behind the hiked petrol tax proposition, saw its support go down 2.5 percentage points to 8.8 percent voter support.

Thursday's poll also showed shrinking support for the far-right Sweden Democrats, who garnered 2.1 voter support.

Demoskop surveyed 1,006 people by telephone between April 28 and May 5.

Recent polls had shown the opposition was widening its lead on the government in voter intentions ahead of the September 19 election.