BRUSSELS - The United States told Russia on Thursday a Kremlin offer to share a radar site in Azerbaijan could not replace US plans to site a missile shield in eastern Europe.

"I was very explicit in the meeting that we saw the Azeri radar as an additional capability and that we intend to proceed with the ... radar in the Czech Republic," US Defense Secretary Robert Gates said after a meeting of NATO and Russian defence ministers.

Secretary of Defense Robert Gates speaks in Singapore June 2, 2007. [Reuters]

Gates played down hopes of an early end to the months-long dispute with Moscow over the shield proposal.

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He said he doubted experts would come up with a full appraisal of the week-old Russian offer before July 1-2 talks between President George W. Bush and Russia's Vladimir Putin.

Gates said Russian Defence Minister Anatoly Serdyukov did not respond during the meeting to his remarks. Diplomats said Serdyukov had earlier repeated that Moscow sees the Azeri proposal replacing the existing US plan.

Gates said he welcomed the surprise offer to share radar data made by Putin at a Group of Eight (G8) meeting last week.

"I repeated our willingness to work and partner with Russia on missile defence," he said.

The United States plans to use interceptors in Poland and radar in the Czech Republic, a configuration Washington says is ideal for blocking any missile, particularly from Iran, heading towards the United States and most of Europe.

Russia has said the US scheme is a threat to its own security and that the proposed US bases on its doorstep could be converted to more dangerous uses in the future.

Washington has said it wants to hold expert-level talks to explore the possibilities of the Russian offer of the Azeri radar, but Gates said he was "sceptical" there would be any conclusions before Bush welcomes Putin in Maine next month.

'Tacit endorsement'

Tension between Washington and Moscow alarmed European NATO members, particularly after Putin threatened to target missiles on Europe if Washington went ahead with building the shield.

The project has also raised concerns it will split NATO into those who would be covered by the shield and those not. Analysts said Turkey, Greece, Bulgaria and Romania would not get full protection.

In what US officials hailed as a tacit endorsement of the US plan, NATO defence ministers agreed to explore building a "bolt-on" anti-missile system that would plug those gaps.

The study should be completed by February. NATO officials hope the alliance can agree by a summit in April in Romania to start work on such a system, which would deploy complementary interceptors to cover southeast Europe.

"We do believe that (our) concerns have been addressed and understood," Bulgarian Defence Minister Defence Veselin Bliznakov told Reuters.

"What we just need is the US (missile shield) and the one which would be added by NATO."

A senior US official, who requested anonymity, said: "What you see here is allies agreeing to adapt NATO's work to the reality that there will be a (US) long-range system."