WASHINGTON (Reuters) - President Barack Obama took a major step toward improving strained ties with Syria on Tuesday, announcing his intention to reappoint a U.S. ambassador to Damascus after a five-year absence.

The White House said Obama had nominated career diplomat Robert Ford to the post. The nomination must still be confirmed by the U.S. Senate.

The United States withdrew its ambassador from Damascus in 2005 after the assassination in Beirut of former Lebanese Prime Minister Rafik al-Hariri. Syria's foes in Lebanon accused Damascus of involvement, a charge Syria denied.

Syrian and Lebanese media have been reporting for weeks that Obama intended to appoint Ford. Now deputy chief of mission at the U.S. embassy in Baghdad, he previously served as ambassador to Algeria from 2006 to 2008 and deputy chief of mission in Bahrain between 2001 and 2004.

A pro-government Syrian newspaper said last week that Damascus had approved a U.S. request to reappoint its ambassador.

Relations between Washington and Damascus have improved since Obama took office 13 months ago. Analysts say Washington is hoping to pull Syria away from Iran and get its help in stabilizing neighboring Iraq.

Nevertheless Obama renewed sanctions against Syria last May, accusing it of supporting terrorism, pursuing weapons of mass destruction and destabilizing Iraq, with which it shares a long, porous border that has been a conduit for al Qaeda fighters.

Syria and Iran are the main backers of Hezbollah, a Shi'ite Muslim political and guerrilla group in Lebanon that fought a war against Israel in 2006.