Yemen's official news agency Saba said Abdullatif Zayani, secretary general of the six-nation GCC, was in Yemen to deliver invitations to both President Ali Abdullah Saleh and his main rival Common Forum to attend a signing ceremony in Riyadh on Monday.
The GCC chief's visit to Sanaa comes a day ahead of a meeting of the group's foreign ministers on Sunday to finalise their plan for Yemen.
The GCC initiative proposes the formation of a government of national unity, Saleh transferring power to his vice president and an end to the deadly protests rocking the impoverished country since late January.
The president would submit his resignation to parliament within 30 days, to be followed two months later by a presidential election.
However, a defiant Saleh, who has been in power for 32 years, has publicly insisted on sticking to the constitution in any transfer of power, even though his ruling General People's Congress party has said it accepts the GCC plan.
Demonstrations calling for the veteran leader's immediate ouster have cost more than 145 lives over the past three months.
The GCC comprises Bahrain, Kuwait, Oman, Qatar, Saudi Arabia and the United Arab Emirates.
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