Iraq's parliament has passed a law forbidding the selling, production or importing of alcohol, in a move that has surprised and angered many in the country's Christian community who rely on the trade.

The law, passed late on Saturday night, imposes a fine of up to 25 million Iraqi dinars, or $21,000 (£17,200), for anyone violating the ban. But according to the Associated Press (AP), it is unclear how strictly the law would be enforced. It could still be struck down by the supreme court.

Although alcohol is forbidden under Islam, it has long been available in Iraq's larger cities, mainly from shops run by Christians. Those shops are currently closed because of the Shiite holy month of Muharram.

The country's parliament, which is dominated by Shiite Islamist parties, announced the ban on its website but did not say how many MPs voted for or against it.

Christian parliamentarian Joseph Slaiwa said the "unjust" ban was slipped into a draft law regulating the income of municipal authorities without law-makers being notified. The original article only called for imposing taxes on liquor stores and restaurants serving alcohol, he said.

"This ban is unconstitutional, as the constitution acknowledges the rights of non-Muslim minorities and ethnic groups who live alongside Muslims in Iraq," he said. "To those Muslim law-makers I say: Take care of your religion and leave ours for us, we know how to deal with it."

Slaiwa added that MPs will submit an appeal at the High Federal Court.

The bill was proposed by Mahmoud al-Hassan, a judge and law-maker from the State of Law coalition, the largest bloc in parliament. He insisted it was in keeping with Article 2 in the constitution, which bans any legislation that goes against Islam.

"The constitution preserves democracy and the rights of non-Muslim groups, but these rights must not violate the religion of Islam," he said. "Some of the law-makers' vote was religiously-motivated, but many others voted to avoid anything unconstitutional."

The publisher of the biweekly newsletter Inside Iraqi Politics, Kirk Sowell said the bill was clearly supported by Shiite Islamists but came "as a bit of a surprise because it has not been a subject of major debate or discussion." He said that the supreme court could strike it down.

Of the other Muslim-majority countries that have laws restricting alcohol, only a few - including Saudi Arabia and Kuwait - enforce a complete ban. The AP reported that the Iraqi law was unlikely to be enforced in the largely autonomous Kurdish region, which is home to a sizeable Christian community.

The bill comes as Iraq is waging a massive military operation to retake the northern city of Mosul from Islamic State, which brutally enforces a ban on alcohol, cigarettes and other drugs in the territory under its control.

Iraqis debated the alcohol ban on social media, with many criticising law-makers for ignoring more pressing concerns, like the war against IS, an economic crisis brought about by low oil prices, and the government's own corruption and paralysis.

A cartoon that was circulating online depicted men with their backs turned on Mosul, shooting a bottle of liquor.