Helicopters and fighter jets belonging to a Saudi-led coalition on Sunday repelled Yemeni Houthi fighters who were pressing a six-day-old offensive to seize Saudi territory, residents and Saudi state television said.

Two residents told Reuters that 20 Houthi fighters had been killed at the southern border of the Saudi provinces of Najran and Jizan, while Saudi state television put the number of Houthi dead at 50.

The Houthis and allied fighters loyal to former president Ali Abdullah Saleh have been trying to capture Saudi territory since March, when a Saudi-led alliance of Gulf states intervened in Yemen to try to reverse the Houthis' seizure of the capital and restore Saleh's Gulf-backed successor, President Abd-Rabbu Mansour Hadi.

Hundreds of Houthi-aligned forces launched a major offensive on the border on Tuesday, capturing three Saudi outposts near Najran and destroying armoured vehicles, according to the Houthi-run Saba news agency.

Further south, the coalition carried out dozens of air strikes in Yemen's central Taiz and Marib provinces. Medical sources and residents said one strike had hit a home in Sirwah, Marib, killing 10 civilians.

The United Nations says that at least 5,700 people, nearly half of them civilians, have been killed and 2.3 million displaced since the Saudi-led coalition began conducting air strikes.-Reuters