Gabon's opposition leader Jean Ping has told the BBC a presidential guard helicopter bombed his headquarters and killed two people.
A government spokesman said the helicopter operation was to root out "criminals" who had set fire to parliament.
Protestors took to the streets on Wednesday claiming fraud after it was announced that President Ali Bongo had been narrowly re-elected.
Some 1,000 people have been arrested, officials say and protests and gunfire continued in the capital Libreville on Thursday.
The official election result, announced on Wednesday, gave Mr Bongo a second seven-year term with 49.8 per cent of the vote to Mr Ping's 48.2 per cent – a margin of 5,594 votes.
But Mr Ping said the election was fraudulent and "everybody knows" he won.
Mr Ping won in six out of nine provinces but disputes the result in Mr Bongo's home province of Haut-Ogooue, where turnout was 99.93 percent and 95 per cent of votes were for the president.
Turnout in the other provinces was between 45 and 71 per cent, according to Gabons interior ministry
- He succeeding his father Omar Bongo who had come to power in 1967 and was Africa's longest serving leader
- Veteran diplomat Mr Ping had served as chair of the African Union
Mr Ping has called for voting figures from each polling station to be made public.
The US and EU have also called for the results to be published, while UN Secretary-General Ban Ki-moon has urged calm.
The Boulevard Triomphal, home to Gabon's parliament, was covered in burnt-out cars and lined with torched buildings on Thursday, reports the AFP news agency.
Police chief Jean-Thierry Oye Zue said six officers had been killed in the protests
