Yemen's Houthis have been targeting ships in recent weeks in protest at Israel's invasion of Gaza, underlining the risks of a conflict that has shaken the Middle East.
The sources confirmed a market advisory that was circulating had been sent by Maersk Tankers.
Denmark's Maersk Tankers, one of the world's leading tanker companies, declined to comment.
"This is primarily a safety option for charterers of cargoes in the light of the day-to-day situation," one shipping source said.
Yemen's Houthis have been targeting ships in recent weeks in protest at Israel's invasion of Gaza, underlining the risks of a conflict that has shaken the Middle East.
The multiple attacks are already raising shipping and insurance costs through the critical Red Sea area.
The narrow Bab al-Mandab Strait connecting the Red Sea and the Gulf of Aden is one of the world's key routes for global seaborne commodities.
The advisory circulated said due to the "rapidly escalating situation in the Bab al-Mandab strait/Yemen", all fixtures and transits through the strait must have the option to proceed via the Cape for safety concerns.
Some shipping companies have already opted to re-route their ships via the Cape away from the Red Sea, adding to journey times and increasing costs.
REUTERS