PHNOM PENH, Cambodia (CNN) - A pact to form a new coalition government in Cambodia has paved the way for Cambodia to regain its United Nations seat and for it to join the Association of South East Asian Nations.

King Norodom Sihanouk departed for China on Saturday following an agreement a day earlier by once-bitter political rivals to form a coalition government, ending a political stalemate which began with disputed elections in July.

The elections gave premier Hun Sen's party victory but not enough votes to form a government alone.

"All the deadlocks are over. There will be no more negotiations, no more talks, no way to have a dispute again and no more demonstrations," said Sihanouk, as he left Cambodia for medical examinations and treatment in China.

On Friday, he presided over the agreement between Hun Sen and opposition leader Prince Norodom Ranariddh, both of whom were on hand Saturday to bid him farewell.

The two had served as co-premiers in a coalition after a U.N.-run 1993 election which the prince's party won. But the partnership was dogged by arguments over power-sharing, and it collapsed.

At the heart of the coalition agreement is the formation of a new upper house of parliament, a Senate.

Hun Sen's party will support the appointment of Ranariddh as president, or speaker, of the lower House, the National Assembly. The president of Hun Sen's Cambodian People's Party (CPP), Chea Sim, speaker of the old assembly, will chair the new Senate.

Chea Sim will serve as acting head of state when the king is abroad -- a duty that formerly fell to the assembly president.

Hun Sen has agreed to royal pardons for five prominent political figures, including two members of the royal family and two of Ranariddh's top military men, convicted on security charges over recent years.

"I am very happy about the success, which I did not expect but everything was so quick," Sihanouk said. He did not give a date for his return to Cambodia.

The king has been a frequent visitor to Beijing for medical check-ups and treatment for various ailments, including cancer.

Ranariddh, asked by reporters how the agreement was reached so quickly, said there was no alternative.

"There was no choice but to find happiness and develop the country," Ranariddh said.

Ranariddh said he and Hun Sen had already agreed on the allocation of six portfolios. He declined to elaborate.

The National Assembly elected in the July 26 poll will hold its first session on November 25. The new government will be set up as soon as possible and legal experts from both parties will work out powers and make-up of the Senate, officials said.

Reuters contributed to this report.