By Sarah Marsh

HAVANA (Reuters) - President Barack Obama's nomination of an ambassador to Cuba is welcome but he should still do more to normalize relations between the two countries during his remaining time in office, a senior Cuban government official said on Wednesday.

Gustavo Machin, the deputy director for U.S. affairs in the Cuban foreign ministry, told a news conference that Cuba will make those concerns known during a bilateral commission meeting on Friday in Washington.

"The Cuban delegation will point out the lack of advances of in the economic, commercial sphere," Machin said. "We consider the measures adopted by President Obama's administration are positive but still insufficient and limited."

Obama on Tuesday nominated career diplomat Jeffrey DeLaurentis, the top official at the U.S. Embassy in Havana since relations were restored last year, to be the first U.S. ambassador to Cuba in more than five decades.

This was "welcome" news, Machin said. Cuba appointed its ambassador to the U.S. a year ago. Still, the nomination must be approved by the Republican-controlled Senate, which is seen as a long shot in a presidential election year and given expected strong resistance from Cuban-American senators including Marco Rubio of Florida and Ted Cruz of Texas.

Obama should also use his executive powers, as he has done in the past, to further hollow out the trade embargo imposed on Cuba after its 1959 revolution, Machin said.

Only Congress can lift the embargo, and the Republican leadership is not expected to allow such a move anytime soon.

"If the president could... allow investment in telecoms, why can't he authorize investments in other areas?" Machin said.

If he allowed the export of certain Cuban products to the United States, why could he not broaden the export of Cuban products?" Machin asked.

Obama's critics meanwhile accuse him of already making too many concessions towards Cuba without getting enough in return.

Republican presidential nominee Donald Trump said earlier this month that if elected he would seek to reverse the detente unless the leaders there allowed religious freedoms and freed political prisoners.

Machin said he hoped the next president would take into account the opinion of the majority of Americans, who agree with the opening to Cuba, according to opinion polls.

Despite the need for more progress still, the two countries have made concrete progress in improving relations over the past four months since a previous commission meeting, Machin said, for example re-launching commercial flights.

(Editing by Alistair Bell)