Royal Dutch Shell is facing a fresh legal challenge over alleged complicity in the execution of nine people killed by the Nigerian government after protests against the oil industry in the 1990s.

Esther Kiobel the widow of one of the “Ogoni nine”, has brought a civil case in the Netherlands. She fought a legal battle to have the case heard in the United States, but it was rejected in 2013.

In 2009 Shell agreed to pay $15.5 million to settle a separate action over the deaths, but it denied the allegations.

A spokesman for Shell’s Nigerian subsidiary, SPDC, said that it had “always denied, in the strongest possible terms, the allegations made by the plaintiffs in this tragic case”. It said that it had appealed…