KYIV, Nov 18 (Reuters) - Ukrainian border guards on Thursday stopped a group of 15 people from the Middle East, believed to be posing as tourists, from crossing the border with Belarus, a statement said, the first such intervention since a migrant crisis escalated in its northern neighbour. Ukraine, wary of becoming a new flashpoint in a migrant crisis unfolding on the border of Belarus and Poland, sent additional forces to reinforce its borders. "Currently, the servicemen of the State Border Guard Service have decided not to allow entry and to return the travellers to the Republic of Belarus, as these persons had no grounds to enter the territory of our state," the statement said. 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. read more Ukraine has accused Russia of helping Belarus foment the crisis, which Moscow denies. Ukraine"s parliament on Thursday passed legislation authorising border guards to use military equipment, firearms and physical force.