Somalia filed a suit against Kenya at the U.N.’s highest court, seeking to resolve a long-running dispute over which country has proprietary right over  lucrative oil reserves in the Indian Ocean.

Somalia asked the International Court of Justice in The Hague to determine the maritime boundary between the coastal nations, saying “diplomatic negotiations, in which their respective views have been fully exchanged, have failed to resolve this disagreement,” a statement issued by the court early Friday said.

Kenyan Attorney General, Githu Muigai, told Reuters he had not yet been served a legal suit but would “take legal steps to defend the interest of the Republic of Kenya”.

Somalia has said the row risks deterring multinational oil companies from exploring for oil and gas offshore east Africa.

Kenya recently identified eight new offshore exploration blocks available for licensing, and all but one of them are located in the contested area.

The row could threaten exploration rights that Kenya has granted to oil and gas companies, which have already started exploring in the area.