NOUAKCHOTT (Reuters) - Mauritania has ordered staff at Israel's embassy to leave the country within 48 hours after freezing ties with the Jewish state over its invasion of Gaza, a senior Mauritanian official said on Friday.

Diplomatic relations between Mauritania, one of only three Arab countries to have full ties with the Jewish state, have been strained since Israel launched a military offensive in the Gaza Strip in December.

The Mauritanian authorities have given staff at the Israeli embassy in Nouakchott 48 hours to leave the country, the official said.

Another official close to Mauritanian military ruler General Mohamed Ould Abdel Aziz said the decision to expel the Israeli diplomats followed the decision in January to freeze relations with the state.

This is the logical consequence of the freezing of relations between Israel and Mauritania ... there is nothing new, said the official, who declined to be identified.

This was expected. After General Aziz took the decision at the Doha summit, an envoy from the Mauritanian Foreign Ministry sent a letter to the ambassador of Israel to leave the country, the official said.

Staff were seen leaving the embassy in Nouakchott.

Abdel Aziz announced the decision to freeze relations at a summit of Arab nations in Doha, Qatar, in January. Qatar said at the time that it would freeze its own relations with Israel, which are at a lower level than full diplomatic ties.

An Israeli Foreign Ministry official who also declined to be identified said Israel had not been officially informed by Mauritania of plans to expel its ambassador.

We don't know what is happening there exactly. We are still checking. They did not tell us they intend to expel our ambassador, he said.

He added that the timing of the decision could be linked to a planned visit to Nouakchott by Libyan leader Muammar Gaddafi. Maybe they are just showing they're tough, the official said.

(Additional reporting by Joseph Nasr in Jerusalem; writing by Daniel Magnowski; editing by Alistair Thomson)