(Updates with EU commissioner's news conference, credit rating)
By Marcin Grajewski
BRUSSELS, May 7 (Reuters) - Slovakia won the green light on Wednesday to adopt the euro in 2009 when it will become the 16th member of the currency area after years of deep reforms that have turned its lagging economy into an investor darling.
Despite European Central Bank doubts about how long Slovakia can hold down inflation, the European Union's executive arm said the nation of 5.4 million people was ready for the euro, unlike bigger EU newcomers Poland, Hungary and the Czech Republic.
If given the final go-ahead by EU finance ministers in July, as expected, Slovakia will become the fourth of the bloc's new member states to join the bloc since 2004 to adopt the euro. Much smaller Slovenia entered the euro zone in 2007, followed by Cyprus and Malta this year.
"This is a significant, historic decision for Slovakia and its people. We are entering an elite group of nations," Slovak Prime Minister Robert Fico said.
The Slovak crown firmed to a new record high versus the euro <EURSKK=>, breaking a psychological barrier of 32.00, in reaction to the European Commission's recommendation.
Credit rating agency Fitch said it expected to upgrade its rating for Slovakian debt.
In a separate report, the ECB said Slovakia met the euro zone entry benchmarks as of March this year but noted there were "considerable concerns" about the country's inflation outlook.
"Looking ahead, the latest available inflation forecasts from major international institutions ... suggest that annual average inflation is likely to rise considerably in 2008 and decrease slightly in 2009," the ECB said.
European Economic and Monetary Affairs Commissioner Joaquin Almunia said Brussels shared the ECB's concerns but finally decided to recommend letting Slovakia in.
"We had some doubts to the extent Slovakia was fulfilling its sustainability aspects of the inflation criterion... Finally our assessment is positive."
The ECB is anxious that euro zone entrants should not only get their inflation down before joining but also keep it down afterwards. Inflation has soared in Slovenia since it adopted the common currency to the highest level in the euro zone, despite a Commission forecast that the rate would remain muted.
The Commission said on Wednesday that new EU member states Poland, the Czech Republic, Hungary, Estonia, Latvia and Lithuania, Bulgaria and Romania were not yet ready for the euro.
Their inflation rates are too high, budget deficits too wide or because they have not yet joined the ERM II currency system, a stability test for euro zone membership, it said.
Those countries are likely to join the euro well after 2010.
Polish Finance Minister Jacek Rostowski said his country's chances for adopting the euro had improved after the Commission's decision on Slovakia.
He confirmed Poland, by far the largest EU newcomer, would try to be ready for the euro in 2011-2012.
TURNAROUND
The recommendation crowns Slovakia's ambitious economic reforms, launched by a previous right-wing government, that have turned the country, once burdened by inefficient Soviet-era industries, into an investors' favourite.
Only 10 years ago, Slovakia faced exclusion from talks to join the EU because of former Prime Minister Vladimir Meciar's anti-Western, autocratic style.
But Slovakia later introduced a flat tax rate and private pension funds and cracked down on abuses of the welfare system, allowing the economy to grow by more than 10 percent last year.
Using the euro will make life easier for Slovakia's biggest investors -- car makers Volkswagen <VOWG.DE>, PSA Peugeot Citroen <PEUP.PA> and Kia Motors Corp. <000270.KS> -- by removing the risk of currency fluctuations.
But many ordinary people, notably pensioners, are worried the euro will bring higher prices, opinion polls show.
The Commission said Slovakia, which accounts for a small fraction of the euro zone's 9 trillion-euro ($14 trillion) economy, met all the entry criteria on inflation, interest rates, its budget deficit, public debt and currency stability.
A country wanting to join the euro must have inflation which is no higher than 1.5 percentage points above the average of the three EU members with the lowest inflation rates.
The Commission said Slovakia's 12-month average inflation was 2.2 percent in March, below the permitted 3.2 percent cap. It urged the country to tighten fiscal policies and keep wage growth under control to combat inflation.
The EU's 27 finance ministers are scheduled to set the final exchange rate between the Slovak crown and euro in early July.
Fico reiterated on Wednesday that he would aim for the strongest possible switchover exchange rate, saying that would allow Slovaks to earn more in euros. (Additional reporting by Krista Hughes in Frankfurt, Jan Lopatka and Michael Winfrey in Prague, Peter Laca in Bratislava; editing by William Schomberg/Ron Askew)