Gunmen in plain clothes opened fire repeatedly on protesters in Yemen's southern city of Taiz on Saturday, wounding 35 people, a doctor said, and a Gulf envoy arrived to try to revive a plan to end the crisis.

Protesters have been demonstrating across Yemen for months in an uprising against President Ali Abdullah Saleh inspired by movements that toppled the leaders of Egypt and Tunisia. A plan negotiated by neighbouring Gulf states for Saleh to step down fell through last month when he refused to sign.

The plain-clothes men, believed to be security officers, fired from rooftops at protesters demanding an end to more than three decades of Saleh's rule in the poorest Arab country.

"There were 35 people with gunshot wounds, three of whom are in an intensive care unit," a hospital doctor told Reuters by phone.

Three people were killed and 15 wounded on Friday when troops shot at protesters in Ibb, a city south of the capital Sanaa. The killings pushed the overall death toll since protests began to at least 170.

Security forces on Saturday arrested Ahmed al Musaibli, a leading broadcaster who had left state television to work for an opposition satellite channel, witnesses said.

Saleh, a wily political survivor, has clung to power despite defections from politicians, army officers and tribal leaders.

GCC envoy in Sanaa

The secretary-general of the Gulf Cooperation Council, Abdullatif al-Zayani, arrived in Sanaa on Saturday for a three-day visit to try to resurrect the power-transfer deal which the GCC brokered between Saleh and opposition leaders.

"The secretary-general will meet Foreign Minister Abubakr al-Qirbi this evening," a Yemeni official told Reuters.

The GCC includes neighbouring oil-rich states on the Arabian Peninsula which share a stake in stability in Yemen.

In remarks published in the Saudi daily Okaz on Saturday, Saleh said that if he lost power he would go out on the streets as the opposition and "bring down the government again".

He said the deal under which he might leave office needed further negotiation.

"There are some clauses in it that are obscure and ambiguous, requiring better clarification through direct talks with the Yemeni groups ... in order to reach an agreement on the implementation timeframe that will follow."

GCC member Qatar pulled out of the plan on Thursday, citing "stalling... continued escalation, and lack of wisdom".

Reuters