Yemen's pro-government forces engaged in intense fighting with the Houthi rebels in the country's southern province of al-Dhalea on Tuesday, causing casualties from both sides, a military official told Sources.

The Houthis dispatched large reinforcements in an attempt to reclaim military sites captured by the government forces in previous battles in Qataba district located in the northwestern part of al-Dhalea, the official said on condition of anonymity.

"Houthis brought large tribal reinforcements from other provinces and apparently insisted on recapturing Qataba district despite the heavy aerial bombardment against their sites," he said.

The source added that the pro-government Yemeni forces clashed with the new Houthi reinforcements and triggered intense confrontations that continued for several hours around Qataba.

He said that warplanes of the Saudi-led coalition carried out airstrikes and targeted the Houthi reinforcements near Qataba, killing and injuring an unknown number of rebels.

A pro-government army commander said that around six army soldiers and 10 Houthi fighters were killed in pre-dawn attacks near Qataba.

Elsewhere in the province, scores of Houthi rebels launched an attack and advanced into government-controlled sites in Al Azariq district in the west of al-Dhalea.

After hours of fighting, the Houthis managed to seize a number of sites from the government forces that withdrew back to other areas in Al Azariq, local military sources said.

On Friday, the government forces, different military units of the local security and army forces launched a large-scale pre-dawn attack against the Houthis in Qataba.

The government forces succeeded in seizing full control over Qataba and the surrounding areas following the military campaign that left scores of rebels killed or injured, a government statement said.

Both warring sides continued to mobilize large numbers of fighters to the frontlines in al-Dhalea amid non-stop armed confrontations taking place since weeks ago in the government-controlled province.

Last week, the UN Special Envoy to Yemen Martin Griffiths tweeted that he is deeply concerned about the ongoing escalation of conflict in al-Dhalea, and urged all parties to exercise utmost restraint.

The UN envoy said that any military escalation risks a setback in the progress towards peace in Yemen.

The areas in the north and west of al-Dhalea have been witnessing continuous fighting between government forces and Houthi fighters for four years.

Yemen has been plagued by a civil war since late 2014 after Houthi rebels revolted and forced the internationally-recognized government of President Abd-Rabbu Mansour Hadi into exile.