WARSAW (Reuters) -The U.N. refugee agency UNHCR and rights groups urged Poland on Tuesday to offer medical and legal support and shelter to migrants camping on the border with Belarus, a day after Warsaw said it would build a fence to prevent migrants crossing.

Poland and fellow EU states Lithuania and Latvia have reported sharp increases in migrants from countries such as Iraq and Afghanistan trying to cross their frontiers. The EU says Belarusian President Alexander Lukashenko is waging “hybrid warfare” with migrants to exert pressure on the bloc.

“While we acknowledge the challenges posed by recent arrivals to Poland, we call on the Polish authorities to provide access to territory, immediate medical assistance, legal advice, and psychosocial support to these people,” said Christine Goyer, the UNHCR’s representative in Poland.

On Monday, Polish Defense Minister Mariusz Blaszczak said that a new 2.5-metre-(8.2-foot)-high solid fence would be built along the border with Belarus.

“States have the legitimate right to manage their borders in accordance with international law. However, they must also respect human rights, including the right to seek asylum,” the UNHCR said in a statement.

Poland’s Foreign Ministry said it fully applies provisions of national and international law with respect to asylum.

“Poland fully respects the Convention Relating to the Status of Refugees and complies with its provisions in the current situation. At the same time, we expect that Belarus, as a party to the Convention, to fulfill its obligations and will provide appropriate care to people in its territory,” a ministry statement said.

The Helsinki Committee for Human Rights said on Tuesday it has requested the European Court of Human Rights take temporary measures to ensure Poland ensures the migrants’ safety, and offer them food, water and shelter at a refugee center.

The Polish Human Rights Ombudsman said Poland’s Border Guard had violated the Geneva Convention by not accepting verbal declarations from some of the migrants that they wanted to apply for international protection in Poland.

(Reporting by Joanna Plucinska; Additional reporting by Anna Koper; Editing by Steve Orlofsky and Mark Heinrich)