SANAA (AFP/Reuters) - Massive protests demanding the ouster of President Ali Abdullah Saleh took place across Yemen on Sunday, as the opposition joined a Gulf Arab meeting in Riyadh to plan for the leader's departure. Security forces were deployed heavily in Sanaa where hundreds of thousands of men and women took to the streets in protest at Saleh's call for an end to men and women demonstrating together against the regime and calling for his ouster. Yemeni forces loyal to President Ali Abdullah Saleh opened fire at an anti-government protest march in the capital Sanaa, wounding at least tenpeople, witnesses said. They said the troops opened fire when the protesters tried to march in a street outside their normal protest zone. Wounded people were being rushed to hospital in ambulances and private cars. Protesters also took to the streets in the cities of Taez and Ibb, south of Sanaa, and the Red Sea city of Al-Hudaydah, the organisers said. "We want to overthrow the regime and to bring the assailant to justice," read their banners. The demonstrations came as foreign ministers of the oil-rich Gulf Arab monarchies were to meet a delegation from the poverty-striken country's opposition in Riyadh, who will ask for clarification on the Gulf initiative on Saleh's departure. The Common Forum, an alliance of the parliamentary opposition, has made Saleh's departure a prerequisite for any political settlement, while the Gulf Cooperation Council's bid to resolve the crisis calls for him to hand over power to his vice-president. Saleh's office has said in response to the mediation bid of the six-nation GCC that he has "no reservation about transferring power peacefully and smoothly within the framework of the constitution". More than 125 people are estimated to have been killed since protests calling for Saleh's ouster erupted in late January, inspired by uprisings which toppled long-time rulers in Tunisia and Egypt. Meanwhile, the opposition was seeking details from Gulf foreign ministers, an opposition leader said. "We will meet with the Gulf Cooperation Council ministers in Riyadh to ask for clarification on their initiative, especially on the departure of President Saleh," Yassin Saeed Noman, head of the opposition Common Forum said. Saleh has since January faced protests calling for his departure, in which more than 125 people have been killed. An opposition delegation - led by Salem Bassandawa, a former foreign minister, and also including Abdelwahab al-Ansi of the Al-Islah party - was to travel to Riyadh later on Sunday, Noman said. The Common Forum has made Saleh's departure a prerequisite for any political settlement, while the GCC's bid to resolve the crisis calls for him to hand over power to his vice president. Saleh's office has said in response to the mediation bid of the six-nation GCC he has "no reservation about transferring power peacefully and smoothly within the framework of the constitution." US and European diplomats have over the past week been working to bring the opposition and Saleh's camp together, a Western diplomat told AFP. "The Common Forum has obtained American and European assurances on the success of the GCC initiative, especially for a rapid departure of President Saleh," said the diplomat, who spoke on condition of anonymity. The opposition has for the time being ruled out dialogue with the regime, and on Saturday threatened not to send its delegation to Riyadh if government representatives were also in the Saudi capital. A source close to the government said "no government representative will go today to Riyadh." The GCC foreign ministers, holding their third such meeting in two weeks, were to "discuss the Gulf initiative concerning the situation in Yemen," said the Saudi state news agency SPA late Saturday.