SOFIA (Reuters) -- Ukraine and Georgia can expect encouragement for their hopes to join NATO at a summit in November, the alliance's head said on Thursday, but entry dates remained unclear given doubts among some existing members.

Ukrainian President Viktor Yushchenko predicted a diplomatic breakthrough would soon create conditions for his ex-Soviet state to join the alliance and that it could secure a "membership action plan" at a NATO summit in Riga in November.

Such a plan is one step short of an invitation to join NATO, although it does not make membership automatic.

Georgia has been hoping to move on from the first stage needed to join NATO -- an "individual partnership action plan" -- to an "intensified dialogue".

At a meeting of NATO foreign ministers in Bulgaria, alliance Secretary General Jaap de Hoop Scheffer said membership was open to those that met criteria on democratic and military reforms.

"There will be a signal in Riga, but the actual invitations to join cannot be expected already at the Riga summit," he told a news conference. De Hoop Scheffer said it was too early to say what kind of signal this would be as it would depend on performance.

Three countries -- Albania, Macedonia and Croatia -- already have action plans and are now waiting for formal invitations.

A European diplomat at the talks in Sofia said indications were that both Ukraine and Georgia would move to their next stages toward NATO membership at Riga, if not before, but there was some wariness about political uncertainty in Ukraine.

"Indications are that they will have it at Riga," he said. ---------Longer wait

However, Albania, Macedonia and Croatia would have to wait longer for their invitations to join, he said. "There is a clear indication there will be no invitation to them at Riga, for which you can read that the United States does not want to extend the invitation then."

Since the 2004 "Orange Revolution" Kiev has sought to push its goal of winning an invitation to join NATO as early as 2008.

However, March elections have failed so far to produce a government and speculation has swirled that Yushchenko's allies in the Our Ukraine party might opt for a coalition with the Regions Party, more sympathetic to Moscow and opposed to NATO.

Washington is seen as a key backer of Kiev's NATO bid. But U.S. Secretary of State Condoleezza Rice skirted a news conference question about the timing of a membership plan.

"The Ukrainian government and people will have to decide whether or not this is something they wish to pursue and they will also have to work very hard to meet the criteria," she said.

A NATO source said a number of countries favoured giving Ukraine a membership plan at Riga, but Rice had not mentioned a specific date to other ministers. Germany was very cautious but Poland urged an upgrade of its status before Riga, he said.

French Foreign Minister Philippe Douste-Blazy was wary.

"All the potentialities of the intensified dialogue are far from being exhausted," he said of the partnership framework launched with Ukraine last year, adding that uncertainty still surrounded the shape of Ukraine's future government.

"Our decisions should be carefully weighed," he said.

Like Ukraine, Georgia has been actively seeking NATO membership, much to the annoyance of Moscow. The NATO source said what would happen with Albania, Macedonia and Croatia remained unclear. "The question is whether we give them in Riga the prospect of joining in 2008 or leave the timetable open," he said.