An "alarming" number of whales are dying off the coast of Ghana, conservationists say, prompting concerns for marine life in the west African nation.

Campaigners believe that a record number of whales have been washed ashore in western Ghana in recent days, and claim they have been affected by oil exploration activities in deep waters off the Ghanaian coast.

"This is a very serious problem – we used to experience around one dead whale every five years, but in the last week alone we have had 16 whales washed ashore," said Kyei Kwadwo Yamoah, programme co-ordinator at Ghanaian campaign group Friends of the Nation.

"We have reason to believe it is related to oil. Almost all of these whales are dying in the part of Ghana where oil exploration takes place. It is well known that seismic exploration can result in the killing of whales," Yamoah added.

Ghana discovered oil in 2007 and currently produces around 110,000 barrels a day.

There have previously been warnings that oil production in the country might affect its whale population. An impact statement in 2009 noted at least 18 different species of dolphins and small whales in the region affected by oil exploration, and said that they would be "vulnerable to disturbance". Oil companies said they would put "mitigation measures" in place, including minimising seismic exploration and helicopter noise in areas heavily populated by marine life.

Tullow Oil Ghana, one of the country's main oil companies, was not available for comment when contacted by the Guardian.

Ghana's Environment Protection Agency (EPA) said there were no links between the oil industry and the beached whales and stated that similar incidents occurred in other countries.

But there is concern over the lack of transparency in regulating the impact of oil extraction on whales and other sea creatures.

"The EPA is not communicating to us and the public. If they are monitoring mitigation, they should publish reports, to show publicly that it is working, or it is not working, and setting out what measures the oil companies should take," said Yamoah.

"For coastal communities, discovering these dead whales is really affecting them psychologically, and they are having to live with the anxiety of not knowing what is causing them to die. Many people believe that their fish may be contaminated."

It's not the first time a link has been drawn in Ghana, which is a major exporter of gold and timber as well as oil, between environmental damage and the extractive industries.

Earlier this year the Guardian reported on the use of mercury in illegal gold mining, causing significant environmental and health risks.