MOMBASA (REUTERS) - Kenyan officials seized 775 pieces of elephant ivory weighing 1.5 tonnes in the port city of Mombasa hidden under fish for export and destined for Malaysia from Uganda, they said on Wednesday.

Poaching has risen in recent years across sub-Saharan Africa, where well-armed criminal gangs have killed elephants for tusks and rhinos for their horns that are often shipped to Asia for use in ornaments and some medicines.

Mr John Changole, deputy commissioner at the Kenya Revenue Authority in charge of port operations, said they had also impounded six bags with polished ivory pieces, all in a 6-metre container that was recovered in a private yard before being taken to the port.

"The ivory was stashed in bundles and sacks and hidden in the fish maws within the container, and was ferried from Malaba (at the Kenya-Uganda border) direct to Mombasa, where it was hidden," Mr Changole told reporters while displaying the ivory at the port. He said no arrests had been made.

A Kenya Wildlife Service (KWS) official put the street value of the ivory at 29.5 million Kenyan shillings (S$430,000).

The seizure comes barely two months after customs officials in United Arab Emirates seized 259 pieces of ivory that also came from Mombasa, a port that has long been seen as a transit point for drugs and other contraband goods, including ivory.

Mr Arthur Tuda, KWS deputy director in charge of the Coast region, said they were yet to determine how many elephants were killed to obtain the ivory, but the tusks came from mature and young elephants, based on the tusk sizes.

KWS said in a report in June that poachers had so far this year killed 137 elephants and 24 rhinos in the country's game reserves, the highest number in a single year.

The government has imposed stiffer penalties on anyone convicted of poaching or trafficking of wildlife trophies, saying poaching was harming tourism, a major foreign exchange earner.