ADEN-- Five people were killed when mortar shells fired by Houthi rebels hit civilian targets in Qaniah district in Yemen's central province of al-Bayda on Monday, a military officer told Xinhua news agency.

"The shells hit some houses killing five people including women. Several people were also injured by the shelling," he said.

The Houthi rebels usually target areas controlled by the Yemeni government with artillery and mortar shellings in revenge for losing areas during ground fighting.

A tribal source told Xinhua by phone that Houthis booby trapped and detonated five houses belonging to those linked with army commanders of Saudi backed Yemeni forces in al-Bayda province.

Meanwhile, Yemeni government forces and its allied fighters engaged in fierce battles with Houthis in several areas, mainly in the western part of the country.

Local residents said that intense fighting coordinated with intensified Saudi led air strikes were still in progress in areas between Taiz and al-Hodeidah port city.

They claimed pro government forces made broad advances and gained control over the Houthi supply lines leading to Taiz province.

Yemen has been locked into a civil war since the Houthi rebels overran much of the country and seized the northern provinces and the capital Sanaa, in 2014.

Saudi Arabia leads an Arab military coalition since 2015 in support of exiled Yemeni President Abd-Rabbu Mansour Hadi.

The United Nations has listed Yemen as the world's number one humanitarian crisis, with seven million Yemenis on the brink of famine and cholera, causing more than 2,000 deaths.