Israel has accused Iran of being behind an attack on an oil tanker in which two crew members - a British national and a Romanian citizen - were killed, BBC reports.
The MV Mercer Street, operated by the London-based company Zodiac Maritime, was off Oman's coast in the Arabian Sea when the incident occurred on Thursday.
The company, which belongs to Israeli shipping magnate Eyal Ofer, said it was working to establish what had happened.
Iran has not commented on the Israeli foreign minister's allegations.
In a statement on Friday, Yair Lapid blamed "Iranian terrorism".
"Iran is not just an Israeli problem," Mr Lapid said, adding: "The world must not be silent."
However, details of the attack on the Liberian-flagged, Japanese-owned tanker remain unclear.
The incident appears to be a serious escalation in tensions in the region, and some reports suggest that a drone was involved.
A spokesperson for the UK government said it was also trying to "urgently establish the facts".
"Our thoughts are with the loved ones of a British national who has died following an incident on a tanker off the coast of Oman," the statement said.
It added that vessels "must be allowed to navigate freely in accordance with international law".
Israeli Foreign Minister Yair Lapad called for a tough response and said he was in consultation with his British counterpart Dominic Raab, and that the issue would be taken to the UN.
