KHARTOUM, April 14 (Reuters) – Sudan’s ruling party, in an apparent bid to heal a rift over accusations of vote fraud, said on Wednesday it would invite opposition groups to join the government if it won elections currently in progress.

Sudan is four days into presidential and legislative polls aimed at helping to bring the oil-producing state back to democracy more than two decades after a military-led coup.

The poll’s credibility was cast in doubt after some main opposition parties decided to boycott large parts of the poll, accusing incumbent president Omar Hassan al-Bashir and his northern National Congress Party (NCP) of widespread rigging.

“If we are declared winners in the elections … we would extend the invitation to all parties, even those who have not participated in the elections, to join the government because we believe this is a critical moment in our history,” senior NCP official Ghazi Salaheddin told reporters.

“We are facing important decisions like self-determination in the south and would like to garner as much support and as much consensus as we can.”

The elections were set up under a 2005 peace accord that ended more than two decades of north-south civil war and also promised a referendum on whether the south should secede in January 2011.

The decision by south Sudan’s dominant Sudan People’s Liberation Movement (SPLM) to boycott the vote and most polls in northern Sudan had raised fears of unrest in the build up to next year’s referendum.

No one from the SPLM or other boycotting groups, including the opposition Umma party, was immediately available to comment on Salaheddin’s offer.

(Reporting by Andrew Heavens; Editing by Simon Cameron-Moore)