Europe's first case of the swine flu emanating from Mexico -- and the first outside the Americas -- was recorded in Spain Monday as the European Union called for urgent talks to confront the threat.
The 27-nation EU also advised against non-essential travel to areas in the United States and Mexico where the deadly virus has surfaced.
Tour groups started cancelling trips to Mexico, while Russia began airport checks, Poland tightened border controls and Bulgaria ordered checks on meat imports from outside the EU to try to hold the disease at bay.
World health officials have stepped up the battle against the new strain of swine flu as Mexico upped the probable death toll from the epidemic to 149 and the United States declared a public emergency. The number of cases under observation in Mexico was more than 1,600.
Spain's health ministry said tests on a 23-year-old man who returned from Mexico last week confirmed he had contracted the disease. Spain has another 20 suspected cases.
Elsewhere in Europe, 17 people in Britain are under observation for possible cases of swine flu as are four in France and five each in Sweden, Denmark and Switzerland.
In Geneva, the World Health Organization's emergency committee was scheduled to meet Monday to decide if the alert level for the swine flu outbreak should be raised.
The EU's Czech presidency summoned health ministers to an urgent meeting, most likely on Thursday, saying "the presidency considers it of paramount importance to coordinate the EU's response to the outbreak," a statement said.
EU Health Commissioner Androulla Vassiliou advised caution for all travellers.
"I would try to avoid non-essential travel to the areas which are reported to be in the centre of the cluster," she said in a video statement.
People "should avoid travelling to Mexico or the USA unless it's very urgent for them," she said, adding that the precaution was necessary "to minimise the personal risk and to reduce of the potential risk to spread the infection."
In remarks to the BBC which qualify her comments about travel to the US and Mexico, she stressed: "I meant advice, not a ban, to Mexico City especially and those states in the US where we have many outbreaks."
Her spokeswoman also underlined she was not advising against travel to Spain.
Spain assured its EU partners it has done all it can to stem the outbreak.
"Spain has taken all the required measures" under WHO guidelines, Spanish state secretary for EU affairs Diego Lopez said at a European Union foreign ministers' meeting in Luxembourg.
Swedish Foreign Minister Carl Bildt and other colleagues appealed for calm.
"Let's wait until the authorities and those that really know have their evaluation of the situation," Bildt told reporters in Luxembourg.
"I don't think we should have undue worries until we know what's happening."
Finnish counterpart Alexander Stubb said: "When you see an epidemic moving as fast as this one you are going to have to do something."
European Commission chief Jose Manuel Barroso said European authorities would remain vigilant.
"We will continue to assess the information we are getting from the experts, evaluate the potential danger and decide together with member states on the measures to take," he said.
Germany's leading tourism group, TUI, cancelled Mexico City visits until May 5, and said it would offer alternatives to clients who had planned to travel to other parts of Mexico.