LAGOS, Dec 10 (Reuters) - The main airport serving the oil-producing Niger Delta in southern Nigeria will reopen for daytime domestic flights on Dec. 18, officials said on Monday, two years after a plane crashed trying to land there.

The international airport at Port Harcourt, the delta's main city and oil hub where foreign companies including Royal Dutch Shell have offices, was closed in August 2006.

The crash during a storm on Dec. 10, 2005, killed 106 people half of whom were school children on their way home for Christmas. An official report said the runway lights were off due to a power cut and the plane burnt on the ground because there was no functioning fire-fighting equipment.

The airport closure was due to last four months and enable the aviation agency to repair the runway and build a perimeter fence, among other improvements. But work has progressed slowly and is yet to be completed.

The Federal Airports Authority of Nigeria (FAAN) said the runway has now been fully refurbished while work on the terminal building was 70 percent complete. The lights and firefighting equipment are also being overhauled, it said in a statement.

"I have just approved the release of more funds for the due completion of all civil works at the Port Harcourt International Airport," FAAN managing director Richard Aisuebeogun said.

The airport will operate only daytime local flights until early next year when it will ready for international and night-time flights, the agency said. Before the closure, Air France and Lufthansa used to fly there.

The crash two years ago came seven weeks after another domestic flight had crashed near Lagos, killing 117 people. The government responded by grounding several domestic carriers and promising swift reforms and investment in aviation.

But 10 months later another domestic flight crashed just after taking off from Abuja. That disaster killed 99 people including the spiritual leader of Nigeria's Muslims. (Reporting by Tume Ahemba; editing by Elizabeth Piper)