Bermuda’s oil tanker operators are seeing their earnings and share prices skyrocket.

Companies such as Nordic American Tankers, DHT Holdings and Teekay Tankers are benefiting from a spike in demand caused by the effects of the US-Iran war.

Attacks on tankers passing through the Strait of Hormuz have constrained traffic on a shipping route used to transport about 20 per cent of the world’s oil supply before the war started.

Oil flows out of Saudi Arabia through an alternative Red Sea route have been further disrupted by Yemen's Houthi rebels, forcing some ships to sail a voyage that’s 30 days longer around Africa.

Nordic American Tankers this week gave some insight into the elevated spot rates the company is able to charge for its fleet of suezmax tankers in a letter to shareholders from Herbjorn Hansson, the company’s chief executive.

The eight spot-rate examples included $200,000 a day for a 60-day voyage, $183,000 a day for a 31-day voyage, and other contracts ranging from $60,000 to $98,000 a day.

Pointing out that NAT’s operating costs are approximately $10,000 a day per vessel, Mr Hansson said: “We are experiencing a market for our vessels that is extraordinary.”

While spot rates are short-term and volatile, longer-term charters have also seen a significant shift higher during the Iran war.

DHT, another Bermudian-domiciled tanker firm, exclusively operates very large crude carriers, which have a capacity of around two million barrels of oil, about double the approximately one million barrels that NAT’s suezmax tankers can carry.

On Monday, DHT announced it had fixed a three-year charter for the DHT Panther at $100,000 a day. In January, the month before the Iran conflict started, the company agreed a five-year charter for DHT Harrier — which, like the Panther is a VLCC built in 2016 — at $47,500 a day.

The latest deal also represents a 33 per cent increase from July, when DHT fixed the 2015-built DHT Jaguar for three years at $75,000 a day.

For companies whose ships make the dangerous trip through the strait, the rewards can be even greater. Bloomberg reported that vessels hauling oil from inside the Persian Gulf to China were being hired at $1.035 million a day, according to data from the Baltic Exchange in London on Monday — the first time the rate had topped $1 million.

Tanker operators’ investors are reaping the rewards. As of yesterday, NAT’s share price on the Nasdaq was up more than 130 per cent for the year to date, while its forward dividend yield was more than 13 per cent, according to Yahoo Finance. DHT’s share price is up close to 90 per cent this year.

Industry experts say the supersized tanker company earnings partly reflect soaring refinery margins. With the world struggling to make enough finished fuels, like diesel and gasoline, to meet demand as the war constrains crude supply, refiners are keen to buy every barrel available to them.