Yemeni government forces were within 40 kilometres (25 miles) of the rebel-held capital Saturday as they pressed their advance against Shiite rebels in disregard of a UN-brokered ceasefire, military sources said.
They were keeping up pressure in Nihm district, Sanaa province, after significant gains in Marib province, east of the capital.
The forces loyal to President Abedrabbo Mansour Hadi, and allied tribes in the area, have laid siege to Nihm's Fardha military, northeast of the capital.
Despite the proximity, the roughly 40 kilometres separating Nihm from Sanaa is mostly rugged mountainous terrain.
On Friday, loyalists seized Hazm, capital of Jawf province, to the northeast of Sanaa.
By Saturday, they had extended their gains in Jawf, capturing Al-Ghayl and Al-Maton districts, according to sources in the pro-Hadi Popular Resistance militia.
The two areas fell after clashes between advancing forces and Huthi rebels and renegade troops loyal to former president Ali Abdullah Saleh, said Ameen al-Ukaymi, a tribal chief of the Popular Resistance.
Government forces are now heading west, toward the contiguous rebel strongholds of Amran and Saada provinces, which lie immediately to the north of the capital, Ukaymi said.
Military sources said pro-Hadi forces, which are supported by a Saudi-led Arab coalition, brought reinforcements to Hazm Saturday, including tanks and armoured vehicles.
The operations took place despite a ceasefire that has been repeatedly violated since it entered into force Tuesday, as UN-sponsored talks began in Switzerland.
US President Barack Obama said Friday there was an "urgent need for all parties to adhere to the ceasefire" after both sides repeatedly violated the truce aimed at helping the talks.
More than 5,800 people have been killed -- about half of them civilians -- and more than 27,000 wounded since March, according to the UN.