South Africa has suspended oil and gas exploration off the east coast following a complaint over the impact of underwater sound pollution on sea life, an official said Thursday.

The government-run Petroleum Agency of South Africa (Pasa) halted seismic surveys along a pristine stretch of coast pending discussions between international oil firms and an environmentalist who blew the whistle on the out-of-season tests.

"The agency has deemed it imperative to suspend seismic operations until the process of consultation is completed, and a report submitted to the agency this week," spokeswoman Althea Adonis told AFP.

Companies compile a three-dimensional map of the seabed by bouncing sound waves off undersea rock formations to detect deposits.

Local environmental consultant Paul Martin complained to Pasa this week over non-compliance with an environmental management programme.

The plan allows for the survey from January to mid-March every year, but explorers had already started in December, which disrupted the seasonal migration of humpback whales, said Martin.

"This is the first stage of oil exploration off the coast and they go and stuff up the first stage. They just ride roughshod over what was agreed," he told AFP.

"We all want sustainable development, but if at stage one those involved aren't going to comply with what is in their authorisation, what trust do we have in them?"

Five international companies, among them Anglo-Dutch Shell and London-based NewAge African Global Energy, have licences for seismic surveys along the east coast from Jeffreys Bay to the Wild Coast.