SANAA/DOHA (Reuters) - Forces loyal to Yemen's exiled government clashed with Houthi fighters over a strategic town close to the border with Saudi Arabia on Wednesday in a sign a new front may be opening in the 19-month-old civil war.

Officials from the internationally recognized government of President Abd-Rabu Mansour Hadi's government said that Yemeni troops captured the al-Buqa border crossing on Tuesday night.

If confirmed, it would be the first time that forces from the Saudi-backed government have established a foothold in Saada province, home of the Iran-aligned Houthi group that controls much of northern Yemen.

"The town is secured but clashes are ongoing," Yemeni Foreign Minister Abdel-Malek al-Mekhlafi told Reuters by telephone.

But the Houthi-appointed Saada governor denied what he said were Saudi media reports suggesting the crossing point had been captured.

"We say this is an illusion. They will be unable to advance one inch inside Yemeni territory," Governor Mohammed Jaber Awad told Reuters.

Fighting has intensified since U.N.-sponsored peace talks in Kuwait ended in August without an agreement. The fighting has been concentrated around the country's Houthi-controlled ancient capital, Sanaa, where little territory has changed hands.

The Saudi-led coalition has been providing air support for Hadi's forces in a civil war that has unleashed famine and killed more than 10,000 people since March 2015 in the Arab world's poorest country.

The outcry over civilian casualties has led some lawmakers in the United States and Britain as well as rights activists to push for curbs on arms sales to Riyadh, so far without success.

EVACUATION

Violence has escalated in Yemen since an attack on mourners in Sanaa last Saturday killed more than 140 people and wounded at least 500 more. The Houthi group has accused Saudi Arabia of carrying out the attack, but Riyadh has denied responsibility.

Saudi Arabia's king on Wednesday offered to help evacuate Yemenis severely wounded in the attack.

King Salman instructed the Saudi-run King Salman Centre for Relief and Humanitarian Aid to evacuate "those whose cases require treatment outside Yemen," said the Saudi press agency, SPA.

It was not immediately clear if the announcement meant that the Saudi-led coalition would lift a ban imposed on flights from Sanaa airport since the peace talks collapsed.

In a sign of escalating regional tensions Iran, an ally of the Houthis, criticized Saturday's air strike, which ripped through a wake attended by tribal leaders.

"Saudi Arabia only has two choices - either admit defeat, stop attacks , exit and accept the results or sink deeper in to the swamp of war crimes and the international court," Hamid Aboutalebi, a political deputy in President Hassan Rouhani’s office, was quoted as saying by Iran state news agency IRNA.

(Reporting by Tom Finn in Doha, Mohammed Ghobari in Sanaa and Babak Dehghanpisheh in Beirut, editing by Sami Aboudi and Angus MacSwan)