President Ali Abdullah Saleh said he supports “peaceful” change in line with Yemen’s constitution as at least 15 more people were killed and more than 130 wounded yesterday with no let-up in protests.

Thirteen protesters and two policemen were killed in violence across the country’s restive south and the capital, officials and medical sources said, as anti-Saleh demonstrators vowed they would not stop.

The deadliest clashes were fought in Sanaa as troops opened fire to break up protests, killing 12 people and wounding more than 130, medical sources said.

Some of the victims were attacked with daggers, the sources said. Government officials said “tens of supporters of the government” were also wounded in yesterday’s clashes.

The demonstrators want Mr Saleh out of power immediately.

Mr Saleh accused his opponents of attempting a “coup against democracy and the constitution.”

“We are not against change as long as it is done by democratic and peaceful means, within the constitution, and with respect to the people’s will,” he said in a statement carried by state news agency Saba. The embattled leader’s comments came after the president and opposition agreed on Tuesday to sign a landmark deal in the coming days for an orderly transition after three months of unrest which has killed more than 140 people.

The Gulf Cooperation Council (GCC), brokering the transition deal, said their foreign ministers would meet in Riyadh on Sunday to work out the modalities of the plan for Yemen.

“Riyadh will host on Sunday an extraordinary meeting for the Gulf Cooperation Council foreign ministers to continue the procedures for the adoption of the GCC initiative,” it said in a statement.