WASHINGTON (Reuters) –
The United States will probably need to deploy more troops to Afghanistan despite almost doubling the size of its force there this year, the top U.S. military officer said on Tuesday.

"A properly resourced counterinsurgency probably means more forces," said Admiral Mike Mullen, chairman of the Joint Chiefs of Staff, told the U.S. Senate Armed Services Committee. He did not say how many more forces would be required.

The United States currently has 62,000 troops in Afghanistan and that figure is expected to rise to 68,000 by the end of the year. There were around 32,000 U.S. troops in the country at the start of the year.

Mullen also called for patience with U.S. efforts in Afghanistan, as the American public and members of Congress -- particularly in President Barack Obama's Democratic Party -- are becoming increasingly uneasy about the war.

Fifty-eight percent of Americans now oppose the war while 39 percent support it, according to a CNN/Opinion Research poll released on Monday.

"We can get there. We can accomplish the mission we've been assigned," Mullen said.

"But we will need resources matched to the strategy, civilian expertise matched to military capabilities, and the continued support of the American people."

(Reporting by Andrew Gray; Editing by Doina Chiacu)