The Nigerian government has said airlines will use the little-known city of Kaduna's airport, about 100 miles north of the capital, while the main airport is undergoing repairs, scheduled to take six weeks from March 8.

"We won't fly from Kaduna during the closure of Abuja airport for six weeks," the Lufthansa spokesman said by phone.

He did not give a reason.

The runway at the main airport had deteriorated to such an extent that some major international carriers refused to fly there, and some aircraft reported damage to their undercarriage.

While it is closed Abuja-bound passengers will have to fly to Kaduna and travel by bus to the capital, guarded by security, on a road where kidnappings have taken place in the past few years.

The plans for Kaduna to handle Abjua flights have been met with scepticism. The airport handled just 12 flights in December 2015, the last month for which Nigeria's airports authority has figures, compared with 812 that used Abuja.

A new terminal is being built but when Reuters visited it last month it was still under construction with cables hanging from ceilings. Contingency plans are in place for the existing terminal to be used.

The temporary closure of Abuja's airport has been criticised by aviation labour unions, business leaders and diplomats.

British Airways, Air France, Turkish Airlines, EgyptAir and Ethiopian Airlines also fly to Abuja.

In October, Dubai-based Emirates stopped flying to Abuja, blaming the state of the runway among other factors, according to the ministry.

(Reporting by Ulf Laessing; Writing by Paul Carsten; Editing by Susan Fenton)

By Ulf Laessing