Military operations have intensified between Yemen's government forces and military units of the Southern Transitional Council, after peace talks between the two rival sides were suspended.
The escalation came a day after STC representatives suspended their participation in the ongoing consultations to implement the Saudi-brokered peace agreement signed last year, reports Xinhua news agency.
The STC's political representatives informed Saudi Arabia late about their suspension that came in protest against the mobilization of government forces in the country's southern province of Abyan.
According to a brief statement released by the STC, the government of President Abd-Rabbu Mansour Hadi "began mobilizing its forces to advance militarily in southern Yemen despite the ongoing talks in Saudi Arabia".
Local military officials confirmed to Xinhua that intense armed confrontations erupted in Abyan using heavy weapons including artillery shelling.
"An unknown number of deaths were recorded as a result of the ongoing battles that are continuing in escalation in Abyan province," one of the officials said.
Meanwhile, Mohammed Naqib, a spokesman of the STC's forces in the province, said that "Abyan front is witnessing violent clashes" and that their forces "fought back strongly against the Muslim Brotherhood-affiliated Islah party forces".
The spokesman of the STC's forces indicated that their forces "are at the highest levels of combat vigilance and ready for all possibilities, including the comprehensive battle", which "will only be a decisive battle".
Yemen's government is yet to comment on the escalating situation in Abyan or regarding the STC's decision of talks suspension.
Earlier this month, a number of military officials of the Saudi Arabia-led coalition arrived in Aden province to closely monitor the situation and prevent any attempts of military escalation in southern Yemen.
But the recent escalation of fighting has threatened to collapse the mechanisms proposed by Saudi Arabia last month to accelerate the implementation of the Riyadh power-sharing agreement signed between the two Yemeni warring sides in November 2019.
The new mechanisms include maintaining a ceasefire and de-escalation between the government and the STC, which came into effect on July 22.
Last year, Saudi Arabia persuaded the STC and the Yemeni government to hold reconciliation talks, which succeeded in reaching a deal to form a new technocrat cabinet of no more than 24 ministers.
The impoverished Arab country has witnessed a civil war since late 2014, when the Houthi rebels overran much of the country and seized all northern areas including the capital Sanaa..