HANOI (AFP) - Russia said today it was not yet ready to join a Chinese-backed treaty making Southeast Asia a nuclear-free zone due to several unresolved "technical" issues.

"We support in principle the treaty on the Southeast Asia Nuclear Weapons-Free Zone (SEANWFZ)," Foreign Minister Igor Ivanov said in Hanoi.

But there were still some "technical issues" being discussed with Southeast Asia, he told a joint news conference at the end of annual security talks involving the Association of Southeast Asian Nations (Asean) and its partners.

"We will be able to find a solution to the issues being discussed," Ivanov said, without explaining the problems involved.

Beijing, which is embroiled in a territorial dispute with several Asean members in the South China Sea, has agreed to ratify the SEANWFZ treaty pending clarification of its exact geographical coverage.

Nuclear-armed India said in May it would honour the pact.

The 1995 treaty binds the Asean members not to develop, manufacture, acquire, possess or have control over nuclear weapons, nor to station or transport nuclear weapons by any means.

The Asean members - Brunei, Cambodia, Indonesia, Laos, Malaysia, Burma, the Philippines, Singapore, Thailand and Vietnam - are also banned from testing nuclear weapons.

Asean wants similar undertakings from the five recognised nuclear powers, including a promise not to send atomic material through the region by any means including nuclear submarine.

Dangerous precedent

The United States, China, Russia, Britain and France have so far agreed not to unleash their nuclear weapons against any of the 10 Asean nations.

But they have been reluctant to give a commitment not to use their weapons against one another in the Asean region as this would be dangerously unprecedented, officials said.

Chinese Vice Foreign Minister Wang Yi said Beijing supported "all the efforts by Asean that are conducive to peace and stability", noting that China was the first country to indicate its readiness to accede to the SEANWFZ treaty.

"We are waiting for the other four nuclear powers to complete their consultations with Asean," Wang told the Hanoi news conference, adding that he hoped for an "early consensus".

China is among countries claiming part or all of the Spratlys, a chain of islands in the South China Sea. The other claimants are Asean members Brunei, Malaysia, the Philippines and Vietnam, along with Taiwan.

China and Taiwan claim the entire South China Sea on historical grounds.