A team of scientists from Fiji, the United States and Saudi Arabia are heading to Kiribati's Phoenix Islands next week, to check on the welfare of the vast coral reef in one of the most remote places on earth.

They'll be looking for signs of impact by El Nino, 13 years after a devastating bleaching event damaged much of the reef during a six month period of constant warming of the ocean waters around the islands.

The reef has rebounded since 2002, but now the scientists want to know if it will be able to resist further warm water stress over the months ahead.

Dr Sangeeta Mangubhai, the expedition's chief scientist, says early reports suggest minor bleaching has returned to the reefs.