LONDON — The migration crisis in Europe is fanning old tensions in the Balkans, prompting a war of words in a region where bloody memories run deep.

Migrants walk in the rain toward the Hungarian border from Botovo, Croatia, on Thursday

Serbia said on Thursday that at midnight, the police had begun to enforce a ban on Croatian goods and cargo vehicles entering the country in what Interior Minister Nebojsa Stefanovic said was retaliation against Croatia for closing its borders, a measure Serbia claimed immediately affected its economy.

The Serbian Chamber of Commerce told the broadcaster B92 that Serbian companies were considering a lawsuit against the Croatian government for economic losses incurred by the closing.

Mr. Stefanovic said that Croatia had not responded to Serbia’s request to open its borders, and he accused the country of engaging in a form of “economic aggression.”

“Serbia has been forced to take these measures,” he said. “We are not satisfied or happy; we are only protecting our country.”

The Serbian response prompted a stern rebuke from Croatia, which accused Belgrade of aggravating tensions.

“We had planned to open the border today, but now we have to react to this,” Prime Minister Zoran Milanovic of Croatia said on Wednesday, referring to Serbia’s actions.

“There will be no war or violence, everything will be calm, but this is not normal behavior” by Serbia, he said, according to Reuters.

Tens of thousands of migrants, blocked from Hungary, have been streaming into the bordering countries of Croatia and Serbia in recent days. Serbia has been busing migrants who arrive in the country almost immediately to Croatia.

Serbia and Croatia are accusing each other of mismanaging the migration crisis, and diplomatic relations have slid to one of the lowest points since the aftermath of the bloody Balkan wars of the 1990s.

The crisis was bound to pose an economic challenge in the Balkan region, where countries with already strained welfare states and high unemployment are not equipped to deal with the sudden influx of people.

Now it threatens to revive old enmities. Historical wounds remain in Serbia and Croatia, which were both part of Yugoslavia before it was violently ripped apart during the Balkan wars of the 1990s.

The New York Times