Unlike the United States, Canada does not require visas for South Korean visitors.
Malaysia, which does not require visas for citizens of Muslim countries, appears to have been the hub.
Mr. Gómez added that he now took groups to Canada, which does not require visas for Mexican citizens.
While the United States has ratified the convention, Mr. Stevenson said it was one of only a few countries requiring visas for shore leave.
Immigration authorities require visas for visitors from Colombia, and the airport police routinely question arriving Colombians and keep their passports until they leave.
Some in Europe are pressing for new sanctions against Israel, like requiring visas for travel or curtailing financing to research institutions.
She said countries already requiring visas for American travelers included the Soviet Union, other Communist countries and some countries in the Middle East, including Saudi Arabia.
They now bought tickets back to Russia, but with a transfer in a European country that required visas for Russian citizens.
