The African Union said on Tuesday it would send a delegation to help resolve a standoff over presidential election results in Gabon that triggered days of deadly riots.

Official results showed President Ali Bongo narrowly held on to power in the central African oil producer last week - but opposition challenger Jean Ping cried foul, claimed he had won the poll and called for a general strike.

"It is an urgent matter and I expect the high-level delegation to be dispatched very soon," African Union spokesman Jacob Enoh Eben said.

Chad's President Idriss Deby, who currently holds the chair of the pan-African body, would likely to lead the talks, he added.

News of the re-election of Bongo, whose family has ruled the OPEC member for 50 years, triggering cries of fraud and riots in the capital that claimed at least six lives.

The government dismissed calls from the opposition and Western powers including former colonial ruler France to publish more detailed results, prompting the justice minister to resign on Monday.

Authorities appeared to have restored order in Libreville on Tuesday and shopkeepers and government workers returned to work despite Ping's call for a mass walk-out.

Parliament was due to resume on Tuesday, with lawmakers set to gather in the Senate building. The National Assembly was set alight and badly damaged during last week's protests.