SANAA (Reuters) - Yemeni political parties agreed on the number of delegates they would each send to a national dialogue conference seen as crucial for the success of a U.S.-backed power transfer deal signed last year.

The deal, announced by U.N. envoy to Yemen Jamal Benomar on Wednesday, means the conference should soon convene to discuss constitutional reforms that would pave the way for presidential and parliamentary elections in 2014.

Restoring stability in Yemen after a year of turmoil that saw long-serving President Ali Abdullah Saleh step down is an international priority due to fears of disorder ripping apart the Arabian Peninsula country that flanks top oil exporter Saudi Arabia as well as major shipping lanes.

Secessionists in the south, Houthi Islamist tribal rebels in the north and al Qaeda militants all benefited from the popular upheaval that ousted Saleh in February.

Southern secessionists, many of them freshly back from exile, Had previously blocked the conference originally scheduled for mid-November, saying they were only interested in separation.

The United Nations Security Council said in a statement the deal should now be implemented "in a serious, transparent, and timely manner, and in a spirit of inclusion and reconciliation".

The agreement gave Saleh's General People's Congress party and its allies 112 delegates, the largest bloc in the 565-seat conference. Southern separatists seeking the restoration of the state that merged with North Yemen in 1990 will have the second biggest bloc with 85 seats.

The remaining seats were distributed between smaller parties, while women and youth groups who camped out in the streets for months demanding Saleh step down after 33 years in office received 40 seats each, according to the document seen by Reuters.

The parties also kept 62 seats vacant for President Abd-Rabbu Mansour Hadi to fill in a way that would ensure that all Yemeni groups are properly represented at the conference.

Benomar said further changes may still be made to adjust the number of seats allocated to southern separatists, women and youth groups.

He also said that southern separatist will be allowed to raise anything during the conference.

A senior Yemeni official said on Monday that Hadi's government had offered southern Yemenis half of the seats of the conference in a bid to bring them on board.

Many southerners complain that northerners based in the capital Sanaa have discriminated against them and usurped their resources. Most of Yemen's fast-declining oil reserves are in the south. The central government denies having a discriminatory policy.

(Reporting by Mohammed Ghobari; Writing by Sami Aboudi; Editing by Jon Hemming)