SANAA (AFP) - Yemen's main opposition warned that a Gulf-led transition plan could end unless the president agreed to it within 48 hours as local officials said three more protesters were killed Sunday. The Common Forum, an alliance of parliamentary opposition groups, repeated its support for the plan to end three months of political unrest but insisted President Ali Abdullah Saleh also commit himself. "We renew our commitment to the Gulf plan but the other party (the president) must also demonstrate its seriousness within the next two days," the Common Forum said. "Any further delay or procrastination on the part of the president to sign the agreement will force us to back the 'choice of the people,' opposing the plan," it said in a statement. The statement came as security forces opened fire to break up demonstrations by teachers at Taez, 200 kilometres (125 miles) south of the capital Sanaa and killed two and wounded at least four more, a local official and medics said. Another man was killed and two more wounded when troops fired at people protesting against fuel shortages in the Red Sea province of Hudaydah, local officials told AFP. The Common Forum accused the Sanaa government of political manoeuvres to delay committing to the Gulf Cooperation Council-initiated plan and asked GCC member states to put a halt to official delegations sent by Saleh's regime. The warning came as a Yemeni delegation led by Prime Minister Ali Mohammed Mujawar on Sunday began a tour of all six GCC states, except Qatar, according to official news agency Saba. President Saleh has accused Qatar of plotting against his country since it openly proposed his ouster. The GCC has said it is awaiting a "signal" from Saleh to revive efforts to end the deadlock in Yemen, which also faces a threat from Al-Qaeda, a sporadic rebellion by Zaidi Shias in the north and a separatist movement in the south. Saleh has reportedly insisted on endorsing the agreement as the chief of the ruling General People's Party (GPC) and not as Yemeni president, a position rejected by the Common Forum. The regime and opposition said on Friday that the GCC chief has requested each side present a list of 15 people to sign the agreement in Sanaa. The GPC said it has presented the list, including its deputy secretary general, Abdulkarim al-Aryani, while the Common Forum said it was preparing the opposition's list. However, representatives of protesters crowding the squares of Yemen's main cities have rejected the initiative since it was first unveiled last month, insisting on the immediate departure of Saleh and on putting him on trial. Around 150 people have been killed since protests demanding Saleh's ouster started in late January. The GCC plan proposes the formation of a government of national unity, Saleh transferring power to his vice president, and resigning after 30 days, a day after parliament passes a law granting him and his aides immunity. GCC Secretary General Abdullatif al-Zayani travelled to Sanaa last week to invite members of the government and the opposition to sign the transition plan in Riyadh and to obtain the president's signature but he returned empty-handed.