NATO and the European Union have accused Iran of attacking a merchant ship in the Arabian Sea and called on Tehran to abide by its international obligations, AP reports.

A British and Romanian citizen was killed in a drone strike on the MV Mercer Street tanker last Thursday. The United States, Israel and Romania blamed Iran for the incident. The latter denied the accusations, calling them unfounded.

NATO spokesman Dylan White said the alliance strongly condemns the recent attack on the MV Mercer Street off the coast of Oman and expresses condolences to Romania and the United Kingdom for the losses.

Meanwhile, the EU deplored the attack, expressed condolences to the victims and called for a thorough independent investigation.

Such actions, contrary to the safety and freedom of navigation in the region, are unacceptable, said spokeswoman for the European Commission.

According to her, all parties concerned must avoid any action that could undermine peace and regional stability.