Three explosions blamed on the Nigerian armed group Boko Haram have killed at least 37 people in a Chadian city on the shores of Lake Chad, security sources have said.

Another 52 people were reportedly wounded in the attacks that struck at around 4:00pm (15:00 GMT) on Saturday, one targeting the fish market at Baga Sola and the other two occurring at a refugee camp on the outskirts of the city.

Lake Chad is shared between Nigeria, Niger, Cameroon and Chad.

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Al Jazeera's Fadhoul Abdul Razzaq, reporting from the Chadian capital N'Djamena, said security forces had not yet confirmed who was behind the attacks.

"There is no information about whether the attackers came from Nigeria or if they were from inside Chad," he said.

Five attackers were also killed in the bombings for which Boko Haram was suspected to be involved, military sources told Associated Press.

Climate change has reduced its surface in recent years, but it contains many islands and islets used by fishermen and its banks have dense vegetation, which makes infiltrations by Boko Haram fighters into Chad much easier.

The Chadian army has since the start of this year been involved in a regional offensive against Boko Haram, whose attacks have spread across Nigeria's borders to neighbouring countries.

At least 17,000 people have been killed, mainly in Nigeria, and more than 2.5 million made homeless since the Boko Haram attacks began in 2009.

Source: Al Jazeera and agencies