UN Secretary-General Antonio Guterres is alarmed by reports of a second consecutive drone attack on a Saudi airport, for which the Houthis rebels in Yemen have claimed responsibility, his spokesman said Wednesday.

"He condemns these attacks, as well as any attack targeting civilians and civilian infrastructure, which violate international humanitarian law," said Stephane Dujarric, the spokesman. "He also calls on all the parties to the Yemen conflict to exercise maximum restraint and prevent further escalation amid heightened tensions."

The secretary-general reminds the parties that a more productive path forward exists -- and that is through dialogue, Dujarric told a press briefing.

Guterres calls on all parties to work constructively with his special envoy for Yemen, Martin Griffiths, to make more progress in the implementation of the Stockholm Agreement as well as efforts to end the four-year-old conflict.

Yemen's Houthi rebels said they launched a new drone attack on Wednesday on Saudi military aircraft hangars at Najran airport on the border with Yemen.

It was the second attack on the airport in less than 24 hours. On Tuesday, a spokesman for the Saudi-led military coalition said a vital civilian facility in Najran was targeted with a drone carrying explosives. The Houthi rebels claimed responsibility for Tuesday's attack and said they targeted an arms depot at Najran airport.

The Saudi-led coalition has been intervening in the civil war in Yemen since 2015 to support the exiled Yemeni government against the Houthi rebels. Houthis have been targeting Saudi border cities since the beginning of the war.