MOSCOW, Aug 18 (Xinhua) -- Russia and Romania accused each other of violation of the diplomatic rules after a Romanian diplomat was expelled from Russia following his arrest by Federal Security Service (FSB), local media reported on Wednesday.

Russia's Foreign Ministry on Wednesday protested in a statement over the decision of Romania to expel Russian diplomat and said it reserved a right to undertake retaliatory measures.

"Unlike a Romanian diplomat detained red-handed, who was in possession of a spy's gear, Russian diplomat has nothing to do with any actions which could justify such decisions. To tie these two issues together means to deliberately contaminate Russian-Romanian relations. We warned Bucharest against these actions but, obviously, good sense did not prevail there," the statement published on the website said.

"We reserve a right to undertake retaliation measures," it concluded.

On Monday, the FSB detained the Romanian diplomat Gabriel Grecu while he was receiving sensitive files from a Russian citizen. Grecu was declared a non-grata person and ordered to leave Russia within 48 hours.

In retaliation, on Tuesday Romania ordered one of the Russian diplomats in Bucharest, who had a diplomatic rank equivalent to that of Gabriel Grecu, to leave the country.

The Romanian Foreign Ministry condemned "the grave violation" by the Russian authorities of the provisions of the Vienna Convention by detaining on the Romanian diplomat.