Yemen's prime minister submitted his resignation to President Abd-Rabbu Mansour Hadi on Sunday amid chaos over reported advances by Houthi fighters on some military buildings and government offices in the capital.
The move by Mohammed Salem Basindwa added to confusion about events in Sanaa, where Houthi fighters were due to sign a deal, brokered by UN special envoy to Yemen Jamal Benomar, intended to end the fighting and pave the way for a new government within two weeks.
"I have decided to tender my resignation from the government (of national reconciliation) out of my concern to pave the way for any agreement reached between the brother leaders of Ansarullah (the Houthis) and brother Abd-Rabbu Mansour Hadi, the president of the republic," Basindwa wrote in the letter, a copy of which was seen by Reuters.
The Yemeni army has deployed tanks around the presidential palace in Sanaa amid clashes between the government troops and Houthi fighters in the capital, eyewitnesses said.
The move came as clashes rage between the two sides in the vicinity of the headquarters of the Sixth Military Zone Command, which is a few kilometers away from the residence of President Abd Rabbuh Mansour Hadi in Sanaa.
Eyewitnesses said that at least 15 Houthi fighters were killed in an ambush by the army against the Houthi gunmen trying to seize the command headquarters.
Clashes raged again on Sunday in Sanaa between government army and Houthis after a few hours of lull with strong explosions being heard in the city.
An Anadolu Agency correspondent reported that clashes re-erupted between the two sides on Al-Khamseen Street in northern Sanaa.
Plumes of smoke are towering over the area amid fierce fighting between the two sides, the AA reporter said.
One Houthi leader told Reuters late on Saturday his group had stepped up its shelling of government forces and had driven soldiers out.
"We controlled a military unit east of the First Armoured Division .... and we continued heavy shelling of the division headquarters and the nearby Iman university in all directions," Ali al-Emad said.
Students and security guards at the university run by Abdel-Majeed al-Zindani, a prominent cleric, were later forced to quit the campus due to the attacks, a university official told Reuters on Sunday.
The clashes came hours before the signing of a deal announced by UN envoy to Yemen Jamal Benomar to end the crisis that has paralyzed the country for weeks.
Benomar said Saturday that Yemeni parties had reached a deal to end the confrontation and it would be signed on Sunday. He did not, however, give further details about the agreement.
On Saturday, Yemen's higher security committee imposed a nighttime curfew in some of the neighborhoods of northern Sanaa.
The committee cited what it described as "security situation developments" and takeover by Houthis of the headquarters of the Yemeni state television in the capital for its decision.
It said in a statement that the curfew would start from 9:00pm local time (18:00 GMT) and come to an end at 6:00am local time (03:00 GMT) every day from Saturday.
The Houthis have been staging mass protests since mid-August to demand the dismissal of Prime Minister Mohamed Basindawa's government and the reversal of a recent government decision to slash fuel subsidies.
Demonstrations turned deadly earlier this month after protesters camped outside government buildings and blocked key roads in the capital to press their demands. Since then, army troops and Houthis have engaged in deadly fighting in several parts of the capital.
Hadi had already offered to sack the government, inviting the Houthis to take part in the formation of a unity government. He also offered to reduce fuel prices.
According to Hadi's proposal, however, the president would retain the right to directly appoint the ministers of "strategic" government portfolios (interior, defense and foreign affairs).
The Houthis, for their part, rejected Hadi's offer and vowed to escalate protests further.
Yemen has been dogged by unrest since a popular uprising that began in 2011 ousted longstanding president Ali Abdullah Saleh one year later.
