Saudi-led warplanes have bombed the Sanaa headquarters of the Yemeni party headed by former president Ali Abdullah Saleh, who is allied to Shiite Houthi insurgents, the party said on Monday.
A provincial source in Lahj, meanwhile, said coalition air strikes on a market claimed 23 lives, although there was no separate confirmation of the toll.
The overnight attack on the offices of the General People's Congress (GPC) caused "some deaths" among employees and guards of the building in the south of the capital, party official Faeqa al-Sayed said.
It came as some GPC members were meeting the UN's Yemen envoy Ismail Ould Cheikh Ahmed in another part of the city.
Sayed called the attack "an attempt to derail the UN envoy's mission".
Cheikh Ahmed arrived in Yemen on Sunday and called for a humanitarian ceasefire after months of conflict in the impoverished Arabian Peninsula nation.
"As we were conducting consultations with the UN envoy to find solutions to the political crisis gripping the country... Saudi forces bombed the party headquarters, killing employees and guards and destroying the building," Sayed was quoted as saying by the GPC's news site, Almotar.net.
Farther south in Lahj province, coalition warplanes struck a market in an attack a provincial official said caused 23 deaths.
AFP could not immediately confirm if the casualties were all civilians, and it was unclear why the coalition had bombed the marketplace.
The Saudi-led coalition began a campaign of air strikes against the Houthis and their allies in March after the insurgents seized Sanaa and then advanced south, forcing the government to flee to Riyadh.
More than 21.1 million people -- over 80 percent of Yemen's population -- need aid, with 13 million facing food shortages.
Upwards of 2,800 people have been killed in Yemen since March, according to UN figures.
Saleh, who ruled for 33 years before being forced from power in 2012 after a bloody year-long uprising, threw the support of his loyalists in the army behind the Huthis.