SANAA (Reuters) – The head of a Persian Gulf bloc trying to mediate a Yemeni transition of power deal that would end the rule of President Ali Abdullah Saleh left Sanaa on Wednesday without securing a signed agreement, a Yemeni official said.

The departure of Abdullatif al-Zayani, who heads the Persian Gulf Cooperation Council (PGCC), suggested that differences remained despite the government and opposition earlier agreeing on the deal in principle.
Zayani had been in Sanaa since Saturday to try to persuade the sides to sign the Persian Gulf-led deal, with help from U.S. and European diplomats.
Earlier, Yemen's president and opposition, pressed by Western and Persian Gulf mediators, agreed in principle to sign a transition of power deal to end the rule of Saleh within a month, an opposition official said.
But in a familiar twist, last-minute snags appeared to be holding up the deal that would grant Saleh immunity from prosecution, allowing him a dignified exit from power in the Arabian Peninsula state that he has ruled for nearly 33 years.
“After American, European and Persian Gulf efforts, there was agreement by the president on the Persian Gulf initiative after simple changes, and the signing will be today,” opposition official Yahya Abu Usbua said.
Al Arabiya television quoted an adviser to Saleh as confirming the signing would take place on Wednesday.
Sources close to the negotiations later said Western and Persian Gulf diplomats were engaged in shuttle diplomacy to try to overcome differences over who would sign and when and where. They said diplomats were insisting the deal be signed on Wednesday.
The United States and oil giant Saudi Arabia, both targets of foiled attacks from Al -Qaeda's Yemen wing, are keen to see an end to Yemen's political stalemate, fearing continued chaos could give the militant group more room to operate freely.
Some political analysts doubt whether the deal, which would help end three months of street anti-Saleh protests that have paralyzed Yemen's economy, would actually be carried out. Two previous near-deals fell through at the last minute.