Forces loyal to Yemen's government on Monday moved military reinforcements to southern border areas in an attempt to discourage the Houthi rebels from intruding into southern regions, a military official said.

"Units of the Southern Transitional Council (STC), which is part of Yemen's government, dispatched armored vehicles and infantrymen to the border areas of the country's southern province of Lahj," the local military source said on condition of anonymity.

"Moving troops to a number of border positions in Al Qabbaytah district came in response to intelligence tips that armed groups were planning a large-scale attack through the territory against the southern provinces," the source said.

"The intelligence tips generated alarm in Aden about the possibility that the rebel forces would carry out attacks against the country's southern provinces," he added.

Another official of the Aden-based STC confirmed to Xinhua that "new local military factions backed by regional countries also increased their presence in key areas in the neighboring province of Taiz."

"A new round of intense fighting might erupt in southern Yemen as many military factions began mobilizing and moving according to their regional backers," the official said anonymously.

"The recent developments might threaten the United Nations efforts that aimed at achieving permanent de-escalation and pushing the Yemeni warring factions into peace negotiations," he added.

On Sunday, Martin Griffiths, the UN Special Envoy to Yemen, arrived at the International Airport in Sanaa, Yemen's capital which is still controlled by the Houthi rebels.

Griffiths began holding meetings with senior Houthi leaders on his first visit to the capital in a year to explore suggestions including a statewide cease-fire in the war-ravaged Arab country.

A recent UN-brokered negotiation between Yemen's warring sides and other relevant parties has failed to reach a cease-fire agreement.

Yemen has been mired in a civil war since late 2014 when the Houthi militia seized control of several northern provinces and forced the internationally recognized government of President Abd-Rabbu Mansour Hadi out of the capital Sanaa.

The Saudi-led Arab coalition intervened in the Yemeni conflict in March 2015 to support Hadi's government.