PARIS, DEC. 4 -- Prince Norodom Sihanouk, the former Cambodian monarch turned rebel leader, announced an agreement with Prime Minister Hun Sen today to work for a political solution to Cambodia's long and bloody conflict.

The agreement, as disclosed by Sihanouk and Hun Sen in a joint communique, contained no practical solution to Cambodia's deep-rooted political and military disputes. But Hun Sen told reporters that, as the first move toward reconciliation, it nevertheless marked a success. He characterized his encounter with Sihanouk as historic.

Sihanouk, acknowledging the accord as preliminary, told reporters "a good bit of the way" remains to be traveled before Cambodia can enjoy peace. But he added, "Together, we will reach it, if not in 1988 then in 1989."

The meeting was Sihanouk's first known negotiation with a high-level official of the Vietnamese-sponsored government in Phnom Penh since Vietnamese troops invaded Cambodia in December 1978 and ended the bloody rule of the Khmer Rouge.

The two leaders, after three days of talks in a French village 60 miles northeast of Paris, called on other Cambodian rebel groups to join peace talks with the Vietnamese-backed government and said an international conference should guarantee the country's independence and an eventual agreement.

They said more talks will be held next month at the village, Fere-en-Tardenois, and at an undetermined later date at Sihanouk's palace in Pyongyang, the capital of North Korea.

The call for "all Cambodian parties in conflict" to join in the talks represented an invitation to Sihanouk's partners in the Chinese- and U.S.-backed rebel coalition, the Khmer People's National Liberation Front, led by Son Sann and the Khmer Rouge. But Prince Ranaridh, a son of Sihanouk who participated in this week's contacts, said Sihanouk and Prime Minister Hun Sen plan to pursue the negotiations even if the other rebel groups refuse to join.

The appeal for an international conference to guarantee any peace agreement appeared aimed principally at Vietnam and China. Although their names were not mentioned, these rival countries exercise influence in Cambodia, with Vietnam sponsoring the government and supporting it militarily and China acting as the rebels' main backer.