According to a statement, Ukrainian border guards prevented a group of 15 people from the Middle East who were acting as tourists from crossing the border with Belarus on Thursday, the first such intervention since a migrant crisis erupted in its northern neighbor.

Ukraine, fearful of becoming a new flashpoint in the migrant crisis brewing on its borders with Belarus and Poland, dispatched more forces to fortify its frontiers.

“Currently, the State Border Guard Service has decided not to grant entrance and to return the travelers to the Republic of Belarus, as these folks had no reasons to enter our state’s territory,” the statement added.

The group, which included four teenagers, had travelled to the Ukrainian border from the Belarusian capital Minsk, and said they wanted to go sightseeing in the western Lviv region before returning home, the statement said.

But the border guards grew suspicious because the group all had passports issued in the same period in September and October. Also, the group weeks ago had arrived in Minsk and immediately headed to the western Grodno region of Belarus that borders Poland, the statement said.

European countries have for months accused Belarus of deliberately creating a crisis by flying in migrants from the Middle East and pushing them to attempt to illegally cross its borders into Poland and Lithuania.

Minsk, backed by Moscow, rejected those accusations in a stand-off that left thousands of migrants trapped in freezing woods at the border. There were signs of the crisis easing on Thursday as Belarus cleared the camps where the migrants had sheltered.

Ukraine has accused Russia of helping Belarus foment the crisis, which Moscow denies.

Ukraine’s parliament on Thursday passed legislation authorizing border guards to use military equipment, firearms and physical force.