Ireland has formally joined South Africa's genocide case against Israel, the International Court of Justice said Tuesday.

The filing, made on Monday, comes months after Ireland announced plans to intervene in the case before the UN's highest judicial body.

“Ireland, acting under Article 63 of the Statute of the Court, has filed in the Registry of the Court a declaration of intervention in the case concerning the application of the Convention on the Prevention and Punishment of the Crime of Genocide in the Gaza Strip,” the court said in a statement on Tuesday.

South Africa brought its case to the International Court of Justice in December 2023, accusing Israel of committing genocide in Gaza. Israel strongly rejected the allegation, calling South Africa’s submission a “despicable and contemptible exploitation of the court.”

In a preliminary ruling in January 2024, the court ordered Israel to curb its attacks in Gaza, and in May ordered the country to immediately halt its military offensive in the southern Gaza city of Rafah.

The United Nations allows states to "intervene" in proceedings if they are parties to the 1948 UN Genocide Convention.

A spokesman for Ireland’s foreign ministry confirmed the application had been filed on Tuesday. “It is important for the court, in considering any multilateral agreement, to understand how the other parties to that agreement interpret and apply it,” he said in a statement.

The filing of the application had been long expected. Last month, the government agreed a plan to present its arguments in the case, with Deputy Prime Minister and Foreign Minister Micheal Martin saying it would be presented in The Hague, where the court is based, within weeks.

“There has been collective punishment of the Palestinian people by intent and effect from Israel’s military operations in Gaza, which have killed 44,000 people and displaced millions of civilians,” Martin said in December, adding that Ireland would ask the court to broaden its interpretation of what constitutes genocide by a state. “We are concerned that an overly narrow interpretation of what constitutes genocide is leading to a culture of impunity that reduces the protection of civilians,” he said.

Experts say the court is not expected to rule on the genocide charge for years to come.

The decision to intervene in the case reflects Ireland's long-standing support for Palestinian civilians, rooted in part in a shared history of British colonialism and in Ireland's own experience of a seemingly intractable sectarian conflict - the Troubles, which ended with the Good Friday Agreement in 1998.

Last month, Israel announced it would close its embassy in Dublin, citing what it said were the “extreme anti-Israel policies of the Irish government.” Israeli officials said the move did not mean Israel was severing diplomatic ties with Ireland.