People in Iraq’s autonomous region of Kurdistan began to cast votes on Monday in a historic referendum on independence from the country, despite opposition from the government, the Supreme Court and other world powers.

The Kurds make up the fourth-largest ethnic group in West Asia and have long wanted to have a separate state of their own. The result of Monday’s vote is expected to be a “yes” for independence from Baghdad, but is not binding, Reuters reported. The Kurds also say the vote acknowledges their crucial contribution in confronting the Islamic State group after it seized control of one-third of Iraq in 2014.

Till 5.30 pm, around 73% of eligible voters had cast their ballots. Voting is expected to go on till 7 pm, Kurdish state media group Rudaw reported. The results are expected on Tuesday.

However, rivals as well as allies of the Kurdish Regional Government are opposed to independence. The Iraqi government, the United States, Iran and Turkey have all called the referendum illegitimate, saying it is a dangerous step towards the division of the country.

The United States is against the referendum as the country fears it would threaten the fight against the Islamic State group, The Washington Post reported. Iran and Turkey believe that the vote would lead to similar sentiments among their own Kurdish populations.

Last week, the United Nations Security Council had said that the referendum could have a “potentially destabilising impact”, while the Iraqi Supreme Court had suspended it. However, President of Iraq’s Kurdish Regional Government Masoud Barzani defended the referendum.

“Is it a crime to ask people in Kurdistan to express, in a democratic way, what they want for the future?” Al Jazeera quoted him as saying. Barzani added that he will hold talks with Iraq’s central government on how to implement the outcome of the vote.