Yemen's General People's Congress (GPC) forces, allied to former President Ali Abdullah Saleh, gained control of key areas in the capital Sanaa on Saturday.
The forces expelled Houthis from Mahwit city and were also able to control the defense ministry complex in Sanaa.
Reports claimed that the Houthi military intelligence chief was detained, while negotiations over establishing a military council to be headed by Colonel Tariq Saleh - nephew of Ali Abdallah Saleh - were also taking place.
Since the start of the clashes, at least 80 people have been killed and 150 others were wounded. Meanwhile, the Houthi militia leader called on Saleh to be reasonable and threatened to “enforce a security dispersal.”
Forces belonging to the GPC also gained "complete control" of the Sanaa Airport from the Houthi militia, an Al Arabiya correspondent reported on Saturday.
The GPC are holding Houthis responsible for "igniting war," a statement from the party founded by ousted President Ali Abdullah Saleh said as fierce clashes erupted in the capital Sanaa.
Forces belonging to the GPC arrested a Houthi leader in Kaziz military camp south of the capital, as there were reports that the building of Yemen's state television was surrounded by the Republican Guard.
Sanaa has been under Houthi militia control since 2015, in a move described as a coup by the legitimate Yemeni government backed by Saudi Arabia and a coalition of Arab countries.
Fierce clashes were also reported near Saleh's home.
The Yemeni GPC called on armed forces and government employees to disobey Houthi orders.
According to Al Arabiya Channel sources, the conflict has also directly affected the capital where traffic flow has come to a complete halt amid safety concerns.
Clashes spread across Sanaa
On Friday, fighting had spread to new areas of the capital in Naqm district of Saouan, the area of Hadda, the political district, Baghdad Street and Sakhr Street.
A number of deaths have been reported on both sides as fighters utilized heavy and light weapons.
Local residents confirmed to Al Arabiya that explosions shook the capital.
Mutual accusations between the Houthis and Saleh loyalists were exchanged across their various news media blaming each other for violating the truce announced on the Friday.
The spokesman for the People's Congress Party, which belongs to Ali Abdullah Saleh, accused the Houthi militias of enflaming the situation in Sanaa after they attacked the house of Brigadier General Tariq Saleh and homes of citizens inside the political district of Sanaa.
“Militias affiliated with the Houthi group violated the truce and attacked the house of Brigadier General Tariq Salih and his brother Mohammed's house, we are coordinating with the mediation committee to monitor the situation,” the website belonging to Ali Abdullah Saleh reported quoting an official source at the Interior Ministry as saying.
The Houthi militia reportedly fired indiscriminate RPGs targeting civilian houses and vehicles.
Houthi news websites have accused the Saleh loyalists of breaking the truce several times despite mediation efforts.
An unnamed security source was quoted saying that Saleh loyalists targeted any one who they though was allied to the Houthi militias with various types of weapons, Houthi media reported.
The last three days witnessed bloody confrontations, in which both sides had dozens killed and wounded, before the announcement on Friday evening of a truce, which did not last for hours.