Plain-clothed gunmen opened fire on protesters in Yemen's southern city of Taiz on Saturday, wounding at least seven people, witnesses said, and a Gulf envoy was due to arrive to help revive a plan to end the crisis.

Protesters have been demonstrating across Yemen for months to try to oust President Ali Abdullah Saleh in an uprising 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 Saleh refused to sign.

The plain-clothed men fired from rooftops in the restive city on protesters who demanded Saleh end more than three decades of rule.

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

The Secretary General of the Gulf Cooperation Council, Abdullatif al-Zayani, was due to arrive 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. – Reuters