BAGHDAD/WASHINGTON Jan 5 (Reuters) - The Iraqi government is beginning the process to remove the U.S.-led international military coalition from the country, Prime Minister Mohammed Shia al-Sudani's office said on Friday.

The U.S. has 900 troops in Syria and 2,500 in Iraq on a mission it says advises and assists local forces trying to prevent a resurgence of Islamic State, which in 2014 seized large parts of both countries before being defeated.

Sudani's statement came a day after a U.S. strike killed a militia leader in Baghdad, prompting anger among Iran-aligned groups which demanded the government end the presence of the coalition in Iraq.

"Government is setting the date for the start of the bilateral committee to put arrangements to end the presence of the international coalition forces in Iraq permanently," a statement from the prime minister's office said.

The committee would include representatives of the military coalition, a government official said.

The U.S. military launched Thursday's strike in retaliation against recent attacks on U.S. personnel, the Pentagon said.

Iran-aligned militia groups in Iraq and Syria oppose Israel's campaign in the Gaza Strip and hold the U.S. partly responsible.

Iraqi PM Sudani has limited control over some Iran-backed factions, whose support he needed to win power a year ago and who now form a powerful bloc in his governing coalition.

"We stress our firm position in ending the existence of the international coalition after the justifications for its existence have ended," Sudani was quoted as saying in the statement.

Islamic State claimed responsibility on Thursday for two explosions in Iran that killed nearly 100 people and wounded scores at a memorial for top commander Qassem Soleimani.

A political adviser close to the Iraqi prime minister said Sudani was falling under huge pressure from powerful Shi'ite parties close to Iran seeking to end the U.S. presence in Iraq and his recent statement was aimed at "appeasing angry parties within the governing Shi'ite coalition against the United States".

Still, it was unclear if Baghdad's announcement on Friday was mainly posturing for internal, political purposes or if the newly announced committee would truly set into motion an inexorable process to end America's military presence in Iraq, a longtime goal of Iran and groups Iran supports.