Unidentified gunmen assassinated a prominent member of the Yemeni opposition coalition in the country's southeast province of Shabwa on Monday, a local police source told Xinhua.

Omar al-Mualim, a leader of the Islamic Islah party in Shabwa, was shot dead by unidentified armed group earlier Monday while he was working in Maifa district in Shabwa, the source said on condition of anonymity.

The source said investigation into the case is under way.

An opposition coalition spokesman in Sanaa, who asked not to be named, told Xinhua that the opposition coalition is working on preparing a statement. He declined to elaborate further.

Islamic Islah Party is the largest ally of the opposition coalition, the Joint Meeting Parties, which also includes the Socialist Party, Nasserite Party and a number of other small factions.

Hundreds of anti-government protesters went Monday to streets in major districts of Shabwa to call for ousting the 33-year ruler President Ali Abdullah Saleh.

Protests against Saleh escalated across the country since he rejected an opposition's peaceful road-map initiative earlier this week.

Inspired by Tunisian and Egyptian protests, thousands of Yemenis have been camping out in major cities, including the capital of Sanaa, since Feb. 11 to press the resignation of Saleh.