Dozens rallied in the Yemeni capital on Thursday demanding the government resign after a law professor representing Shiite Huthi rebels at reconciliation talks was shot dead this week.
"The people want to overthrow the government," chanted the protesters, who gathered in response to calls by the Huthi rebels, known as Ansarullah (Partisans of God). "Government of corruption, leave the country."
On Tuesday, gunmen in Sanaa shot dead Ahmed Sharafeddin as he drove from his house in the capital Sanaa to the hotel where the final working session of the talks was being held.
He was the second Huthi representative to the talks to be killed, with MP Abdulkarim Jadban shot dead in a similar attack in November.
Protesters took off from the Saba roundabout in central Sanaa where Sharafeddin was killed and marched towards the government headquarters carrying portraits of the slain envoy.
In a statement, they described Sharafeddin's killing as "shameful" and accused the government of "plotting, collaborating with, and protecting criminals."
"We demand the overthrow of the so-called consensus government, which has failed to provide us with security, stability, and protection," said the statement read by one of the protesters.
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The killing of the Ansarullah representative came as fighting between Huthis and powerful tribes resumed in the northern Amran province after a series of ceasefires brokered by the government.
A day of clashes left 20 people dead there on Tuesday.
Analysts have said the Huthis are trying to seize more territory in the north in anticipation of the conclusion of a national dialogue that could turn Yemen into a federation of regions.
The latest round of fighting erupted on January 5 when Huthis tried to seize strongholds of the powerful Hashid tribe in the north.
The Huthis launched the attacks against Hashid tribesmen in retaliation for the tribe's support for hardline Sunni Islamist groups fighting the Huthis in Dammaj.
Despite the fighting, national talks aimed at drafting a new constitution are to be concluded in a ceremony on Saturday in Sanaa.
President Abdrabuh Mansur Hadi, who arrived at Tuesday's session after hearing of Sharafeddin's killing, told delegates in an impassioned speech that "the dialogue will continue, and evil forces will fail."
Some Huthi members walked out after receiving news of the killing, as the powerful Sunni Islamist Al-Islah (reform) party urged a probe.