(Adds airport using second runway)
TRIPOLI, March 21 (Reuters) - Libyan authorities closed the airport in the capital Tripoli on Friday after rockets hit a runway on Friday, officials said.
"Flights were halted but the airport has been reopened using a second runway," a spokesman for the transport ministry told a Reuters reporter visiting the airport. The reporter saw no planes taking off or landing.
"We cancelled all flights," said the country head of a foreign airline with several daily flights to Tripoli.
Maintenance teams were clearing the first runway of debris, the spokesman said, adding it was unclear who had fired the rockets which landed at dawn.
Gunfire could be heard during the night in the capital, residents said.
Libya's government struggles with militias that helped overthrow Muammar Gaddafi in 2011 but which have kept their guns to demand power, oil wealth and influence. (Reporting by Ulf Laessing, Hani Amera and Feras Bosalum; Editing by Catherine Evans)