(Recasts after first summit session)
By Ilona Wissenbach and Paul Taylor
BUCHAREST, April 2 (Reuters) - NATO leaders failed to agree at the start of a summit on Wednesday to put former Soviet republics Ukraine and Georgia on a path to membership or to invite Macedonia to join the alliance.
The double setback for U.S. President George W. Bush at his final NATO summit overshadowed agreement to invite two new Balkan countries -- Croatia and Albania -- to join the 26-nation defence alliance and progress on extra troops for Afghanistan.
NATO spokesman James Appathurai hailed a breakthrough on Afghanistan after French President Nicolas Sarkozy offered up to 1,000 extra troops for the east, enabling the United States to redeploy forces to the south, scene of the fiercest fighting with Taliban insurgents.
That in turn enabled Canada to say its parliamentary conditions had been met to stay on in Afghanistan, where it has suffered heavy casualties at the hands of Islamist guerrillas.
"There is a clear unity within the alliance that this mission must succeed, that it will succeed," Appathurai told a late-night briefing. "All of the allies reiterated this will be a long term commitment."
However, on enlargement, he acknowledged the lack of agreement on the main disputes going into the Bucharest summit.
The leaders agreed both Ukraine and Georgia were entitled to apply to join NATO and that it was "not a matter of whether but of when", the spokesman said.
But he said he did not expect either to be granted a Membership Action Plan (MAP), a gateway to eventual accession, this week.
Germany and France had led opposition to the move, saying that neither aspirant met NATO's criteria yet, and that the decision would be an unnecessary provocation to Russian President-elect Dmitry Medvedev.
"NOT RIPE"
German Chancellor Angela Merkel reaffirmed on arriving in Bucharest that both countries should have a long-term prospect of NATO membership, "but there is one difference with the United States: we believe the time for MAP is not ripe".
At stake was whether NATO pushes its European borders right up to the frontiers of Russia, with the exception of Belarus, or leaves a strategic buffer zone as the Kremlin wishes.
Bush had strongly urged sceptical European allies earlier to reward both countries for their democratic revolutions and not to allow Moscow a veto over NATO decisions.
"My country's position is clear -- NATO should welcome Georgia and Ukraine into the Membership Action Plan," he said.
A senior U.S. official said no formal consensus had been reached at the dinner and decisions would be taken on Thursday.
"The issue of exactly how to proceed on that decision was not resolved," the official said of Ukraine and Georgia, voicing hopes that leaders would do a "lot of thinking overnight".
On the other enlargement issue, Spanish Foreign Minister Miguel Angel Moratinos told reporters: "For the moment, Greece is not in a position to agree to the entry of Macedonia, and it will be Croatia and Albania first."
Athens threatened to veto Skopje's entry over an unresolved dispute about the former Yugoslav republic's name, which is the same as the most northerly Greek province.
"We have said that no solution means no invitation," Greek Foreign Minister Dora Bakoyanni told reporters.
Analysts have said a rebuff for Macedonia could destabilise the fragile, ethnically divided state with knock-on effects throughout the region.
Bush sought to soothe Russian anger over what Moscow sees as NATO's attempt to encroach on its sphere of influence, saying the Cold War was over and Russia was not the West's enemy.
Looking ahead to a weekend summit with Russian President Vladimir Putin, Bush said there could be an unprecedented level of strategic cooperation on missile defence and arms control.
Amid blanket security that shut down much of central Bucharest, police broke into a factory in Bucharest that has been rented by a group of anti-NATO protesters and took away 46 suspected activists for identity checks. (Additional reporting by Susan Cornwell, Matt Spetalnick, Justyna Pawlak, David Brunnstrom, Sabina Siebold and Randall Palmer in Bucharest; Writing by Paul Taylor and Mark John; Editing by Timothy Heritage)