Research published in natural science journal "Nature" accused Greenpeace of not caring for facts when it criticized the dumping of the Brent Spar tanker, and accused the group of exaggerating the volume of oil that was stored in the tanker. Greenpeace had claimed that the tanker contained 5,500 tonnes of crude oil, while Shell estimated it only contained 50 tonnes. However, the measurements had been made under duress during a protest occupation of the platform, since Shell had refused permission, and Greenpeace activists had been under attack by water cannons and the like. The BBC issued an apology to Greenpeace for having reported that the NGO lied.