By Mohammed Sudam SANAA Yemeni President Ali Abdullah Saleh said protesters demanding an end to his 32-year rule could not achieve their goal through "anarchy and killing," after nationwide unrest which has killed 12 people since Thursday.
In the latest violence, soldiers shot dead a teenager in the southern port city of Aden on Monday. Four others were wounded when the troops fired on youths throwing stones at their patrol.
Most of the deaths have been in Aden, where many people resent being ruled from the north. But poverty, corruption and soaring unemployment have fueled protest against Saleh's government across the Arabian Peninsula's poorest state.
Protesters, inspired by the overthrow of veteran leaders in Tunisia and Egypt, have demonstrated in the capital Sanaa and thousands have held sit-ins in several Yemeni cities.
Saleh has pledged to step down in 2013 and reform parliamentary election laws, but his call for dialogue has been rejected by opposition parties who say they cannot negotiate with a government they say is using violence against protesters.
Saleh also accused his opponents of trying to use force.
"Yes to reforms," he told a news conference in Sanaa. "No to coups and seizing power through anarchy and killing."
"If they want power they must reach it through the ballot boxes .... You are calling for the regime to go -- then come and get rid of it through the ballot boxes."
Saleh, an ally of the United States in its battle against a resurgent al Qaeda wing based in his country, also faces a separatist revolt in the south and is trying to maintain a shaky truce with Shi'ite Muslim rebels in the north.
Protests have taken place across Yemen, a country of 23 million which borders the world's top oil exporter Saudi Arabia.
Thousands of people have protested in the cities of Ibb and Taiz, as well as in two districts of Aden, where security has been stepped up and tanks and armored vehicles have been deployed on main streets.
Residents said many shops were closed in Aden and parents were keeping their children away from school, though markets were still open.
The leader of the secessionist Southern Movement, Hasan Baoum, was arrested on Sunday by an "armed military group" which took him from an Aden hospital where he was being treated, his son, Fadi Hasan Baoum, told Reuters.
In the town of Yahr, north of Aden, witnesses said gunmen took over government buildings on Monday in protest at the death of a demonstrator in Aden the day before.
Witnesses said around 3,000 people had also launched a sit-in outside Sanaa University, scene of regular demonstrations against Saleh. Some were holding banners saying "Leave" and "The people want the overthrow of the regime."
Saleh has repeatedly called for dialogue with opposition parties and blamed the protests on "elements outside the system and the law."
But the coalition of main opposition parties, including the Islamist Islah and the secular Socialist Party, said on Sunday there could be no dialogue with "bullets and sticks and thuggery," or with a government "which gathers mercenaries to ... terrorize people."