A Nigerian native posing as a diplomat was detained Tuesday as he tried to enter the Ritz-Carlton hotel where U.S. President Barack Obama was staying with his family, Moscow police said.

Police officers guarding Tverskaya Ulitsa, where the hotel is located, noticed the man loitering around the hotel and stopped him as he tried to mingle with Obama’s security detail, police said.

“The man provided documents saying he was Prince Henry Obasy, a diplomat with Nigeria’s embassy in Moscow, and he said he had received [the documents] from the Foreign Ministry’s state protocol department,” Viktor Paukov, police chief for Moscow’s central district, said in a statement.

The papers turned out to be fake and he was detained. The man refused to elaborate on what he was doing at the hotel, police said.

The Foreign Ministry told police that it had not registered anyone named Prince Henry Obasy, and the Nigerian Embassy denied having a diplomat with that name.

Police have opened an investigation on the matter.

Obama and his wife, Michelle, traveled around Moscow for meetings for most of the day Tuesday, while their two young daughters stayed at the hotel with their grandmother.