The Slovak embassy in Hungary has been attacked but got off lightly when two supposed Molotov cocktails thrown at the entrance failed to ignite. No one was hurt and no one immediately claimed responsibility.
A Foreign ministry source said the incident reflected a period of increased sensitivity in Slovak-Hungarian relations.
Hungarian President Laszlo Solyom cancelled a private visit to Slovakia on Friday after Bratislava called it a provocation. It was the anniversary of the 1968 Soviet-led invasion of what was then Czechoslovakia, when the Hungarian army formed part of the invasion force.
Solyom had been invited by the local authority of the mostly ethnically Hungarian town of Komarno to attend the unveiling of a statue of Stephen I, the first king of Hungary a thousand years ago.
The incident showed rising tensions between Bratislava and Budapest, which have had frequent diplomatic clashes about the treatment of the ethnic Hungarian minority in Slovakia. Both countries, EU member states, clearly criticised the act against the embassy as a rogue attack.