THE reported deaths of 2400 sheep during a live export voyage from Western Australia will be investigated.

Figures showed a mortality rate of 3.76 per cent on a journey from Fremantle to Kuwait, the United Arab Emirates and Qatar in August, which was above the reportable mortality level of two per cent.

WA Agriculture and Food Minister Alannah MacTiernan instructed the Department of Primary Industries and Regional Development to investigate.

She said there might be a seasonal correlation between heat and animal welfare.

"Our legal advice is that WA's animal welfare laws apply on live export ships (and) as a government, we have an obligation to see those laws followed," she said.

Ms MacTiernan has written to the federal minister to suggest a collaborative approach to the investigation.