Dollar revenues from Egypt's Suez Canal are down 40% from the beginning of the year compared to 2023, canal authority head Osama Rabie said on Thursday, after attacks on ships by Yemen's Houthis caused major shippers to divert away from the route.

Ship traffic was down 30% in the period between Jan. 1 and Jan. 11 compared to a year prior, Rabie said, speaking on a late night talk show.

The number of vessels to pass through the Suez Canal dropped to 544 so far this year, from 777 in the equivalent period of 2023, he said.

The Suez Canal is a key source of scarce foreign currency for Egypt, and authorities have been trying hard to boost revenues in recent years, including through an expansion of the canal in 2015. A further expansion is under way.

Yemen's Iran-aligned Houthis have been attacking commercial vessels in the Red Sea for weeks to show support for Palestinian militant group Hamas in its fight against Israel.

Many commercial shippers have diverted vessels to other routes. The United States announced last month a new international mission to patrol the Red Sea and deter attacks.

Rabie said only ships that had to proceed promptly with their journey had diverted around the Cape of Good Hope, and that others were waiting for the situation to stabilise.

The security concern to shippers could not be overcome with discounts or other incentives offered by the canal, he said.

"A very large portion of the goods will return (to the Canal) once this matter is finished," he said, in reference to the Houthi attacks.