The Norwegian Maritime Authority barred ships from calling at ports in part of the Red Sea and restricted transit through the area as Houthis continue to threaten shipping in the region.

Oslo’s decision to lift its maritime security alert status to Level 3, the highest tier, in the Red Sea has led at least one ship operator to avoid transiting the region.

Heogh Autoliners said its car carriers will not make “ordinary transits” through the affected area for the time being.

“The safety of our crew, cargo, and vessels remains Hoegh Autoliners’ top priority,” the Oslo-listed company said in a stock exchange announcement.

VesselsValue tracking data shows the company’s 8,500-ceu Hoegh Trapper (built 2016) has just successfully transited the Bab el-Mandab Strait from the Gulf of Aden and is sailing north to the Suez Canal.

“We will continuously review our policies based on recommendations from relevant authorities and update these as appropriate,” the company said.

The Norwegian Maritime Authority’s Level 3 alert status means ships can transit the southern Red Sea if “deemed justifiable” by their operators, though they cannot make port calls in the affected region.

Knut Arild Hareide, Norway’s director general of shipping and navigation, cited the recent spate of attacks on civilian ships for the authority’s decision, noting that while the Houthis had claimed they would only target vessels with ties to the conflict in Israel and Gaza, there is uncertainty around the information used to target vessels.

“While Norwegian ships are not prohibited from navigating through the area, the elevated security level sends a clear message that the situation is ambiguous and has worsened,” he said in a statement. “Traffic in the area should be avoided.”

On Tuesday, Oslo-listed car carrier operator Wallenius Wilhelmsen also said it is rerouting all vessels scheduled for Red Sea transits. They will now travel via the Cape of Good Hope.

“The safety of our people is our number one priority,” chief executive Lasse Kristoffersen said.

“As a result of the current security situation in the southern parts of the Red Sea, Wallenius Wilhelmsen has until further notice decided to reroute all vessels to avoid the area. We will continue to monitor the situation closely and stay in direct consultation with authorities, industry bodies and all relevant counterparts.”

The company said it has no vessels in the area at present, and that rerouting will add one to two weeks to voyage durations.

Norway is one of 10 nations that have joined US-led Operation Prosperity Guardian, a military effort aimed at restoring maritime security in the Red Sea and Gulf of Aden.

It is also a member of NATO, which joined the US, European Union and nine other countries in condemning Houthi interference with navigation in the region, including attacks on ships and the “appalling” detention of the crew of the 5,100-ceu car carrier Galaxy Leader (built 2002).

“Such behaviour also threatens the movement of food, fuel, humanitarian assistance, and other essential commodities to destinations and populations all over the world,” the signatories said.

“The undersigned further encourage all states to refrain from facilitation or encouragement of the Houthis. There is no justification for these attacks, which affect many countries beyond the flags these ships sail under.”