Two major players, Odfjell of Norway and A P Moeller-Maersk of Denmark, have already announced that part or all of their fleets will sail around the Cape of Good Hope instead of through the pirate-infested Red Sea.

"Yes, there are owners who are taking that option to go around the Cape of Good Hope instead of through the Gulf of Aden" said Thomas Timlen from the Denmark-based Baltic and International Maritime Council.

Timlen said on the sidelines of a regional maritime conference that the switch would incur expensive delays of up to three weeks in shipping times.

"It is unfortunate that at a time like this when the global economy is such, that shipping companies would have to take measures which would incur more cost. There would definitely be delays of up to two to three weeks," he said.

Peter Swift of the London-based International Association of Independent Tanker Owners (Intertanko) said the re-routing would increase costs by about 30 per cent on a typical voyage.

"Some tanker owners have decided not to do business in that area and take the Cape route as an alternative," he said.

But with pirate attacks becoming more frequent and violent, Robert Holt from the International Association of Dry Cargo Ship Owners (Intercargo) said the costs of re-routing were justified.