Hearing over the Kenya-Somalia sea border dispute at the International Court of Justice (ICJ) begun on Monday despite Kenya's absence.
The case started with oral arguments by the Somalia government's legal team.
The ICJ has said it "regrets the decision of Kenya not to participate", but ruled to continue the hearing without the country's involvement.
Somalia said Kenya's decision not to participate in the ICJ proceedings was "inconsistent with its obligations.. and rule of law."
The bench also rejected Kenya’s request to address the council before the start of the hearings.
Kenya had sought to address the court on why the country may not participate in the hearings of the case that started in 2014.
Kenya accuses the ICJ of bias in the case, which concerns a 62,000 sq miles (160,000 sq km) triangle in the Indian Ocean.
Somalia brought the case in 2014, saying the maritime frontier should follow on in the same direction as the land border, while Kenya argues that it has always been taken in a horizontal line from the point where the two countries meet at the coast.
