LONDON - Police investigating the discovery of "potentially explosive material" at a house in northern England arrested a second suspect under anti-terrorism laws on Saturday.

The 31-year-old man was detained in Dundee in the early hours, a Humberside Police spokeswoman said.

Another man, also 31, was arrested on Wednesday after police seized the unidentified material during a house search in the centre of Goole, East Yorkshire.

Police sealed off the area around the house during the searches and tests are being carried out on the material.

The men, both from Goole, have not been named. They were detained under the Terrorism Act 2000 and are being questioned at a West Yorkshire police station.

Police said the house in Goole was searched as part of a separate criminal investigation.

"We would ask people to go about their business as usual," a police spokeswoman said. "However, we would always urge people to remain vigilant."

Police stepped up patrols earlier this year after two car bombs were found in central London and a Jeep was rammed into a terminal at Glasgow Airport.

The security service MI5 rates the current threat of a terrorist attack as severe, the second-highest level. That means an attack is thought to be "highly likely".