Three men and two women suspected of terrorist offences have been arrested in Britain just days ahead of Thursday's summit meeting of Group of 20 (G20) nations, police said Monday.
Police said the arrests were made over the weekend in port city of Plymouth, south-west Britain, after officers uncovered a cache of weapons and suspected extremist material during a house search, reported dpa.
Devon and Cornwall Police said the officers found weapons, imitation weapons, suspicious devices and "material relating to political ideology."
The Daily Telegraph said in a website report that "bomb-making equipment" had been discovered.
But police had played down the suggestion that there may have been a plot to cause death or injuries, suggesting instead that the explosives which were allegedly seized were intended to cause "disruption," the Telegraph said.
London police has said it faced a "huge challenge" from an estimated 100,000 anti-globalization protestors expected to join demonstrations in the British capital later this week.
Police fear the rallies, on April 1 and 2, will be hijacked by anarchists intent on sparking violence and riots, with thousands of hardline protestors expected to fly in from abroad.
Police said the investigation is not linked to any particular religious group and centres around "political activity involving British nationals."