UPDATE 1-Norway's right-wing government ahead in poll -Aftenposten

* Election day is Sept. 11

* Graphic: http://tmsnrt.rs/2ugJCjo (Adds second poll, detail)

OSLO, Aug 31 (Reuters) - Support for Norway's right-wing government and its two centrist backers rose on Thursday in an opinion poll published by daily Aftenposten, indicating the coalition may be able to stay in power after the Sept. 11 election.

For much of the year, Labour and its centre-left allies were significantly ahead in polls and favoured to replace Conservative Prime Minister Erna Solberg's government. But support for the opposition has slipped as the economy recovered.

The Aftenposten poll of 1,003 voters showed the ruling parties and its supporters could win 88 seats in parliament, ahead of the 85 needed for a majority, while the main opposition Labour Party and others on the centre-left would win 81 seats.

A separate poll by daily Vaart Land also showed the government gaining ground when compared with a survey conducted in June, but not enough to overtake the opposition.

The Vaart land poll gave Labour and the centre-left 86 seats against the government's 83.

With less than two weeks to go, even small changes in support for some of the nine parties on the left and right could ultimately decide the outcome.

(Reporting by Terje Solsvik and Camilla Knudsen, editing by Gwladys Fouche)