The relentless political turmoil in Yemen took another deadly twist when the governor of the Marib province was stabbed during yet another anti-government protest.

BBC Arabic reported that Governor Ahmed Naji al-Zaidi was stabbed in the neck by armed men who attacked his convoy. He has been hospitalized in nation’s capital Sanaa.

The violence incident followed the death of six people, including a 12-year-old boy, on Saturday in a confrontation with riot police in Sanaa. There were also violent clashes in Tahrir Square where hundreds of policemen reportedly used tear gas, water cannons and live bullets against protesters who have camped out there.

On Monday, demonstrators in the port city of Aden set a police station ablaze. AP reported that clashes have also occurred in the southern provinces of Hadramawt, Taiz and Hudaydah, and in Jawf in the north-east.

So far, about thirty people have been killed in clashes between state security forces and demonstrators who are demanding sweeping changes in the country and the immediate resignation of President Ali Abdullah Saleh, who has ruled the poverty-stricken country for more than three decades.

While the U.S., a key ally of Yemen, has asked opposition groups to negotiate reform measures with Saleh, they apparently refuse to talk unless Saleh quits immediately.

The U.S. has called for a peaceful transition of power in the country and asked Saleh to investigate the deaths of protesters.

The US government is strongly on record as defending the rights of citizens to demonstrate peacefully, the U.S. embassy in Sanaa said in a statement.

The Embassy also rejects any allegation that the U.S. government has somehow condoned the use of violence by any side.”

As for Saleh, last week he proposed to change the government into a more parliamentary system and plans to hold a referendum on it later this year. However, he said he will not step down from office until his current term expires in 2013.

Saleh has also fired his cabinet minister who was in charge of leading talks with the opposition, Hamoud al-Hattar, and replaced him with another minister.

Abdelbari Dugheish, a member of parliament from Saleh's ruling party, has now switched to the opposition.

The security forces are responsible for the loss of lives. They are firing at random and using excessive violence, he said.