U.K. police arrested nine more people as part of terrorism probes throughout the south of England a week after officers raided suspected Islamic extremists in London.

The Metropolitan Police Service said last night that they conducted raids at four homes and a business as they detained three more men as part of last week’s investigation. Separately, Thames Valley Police said they arrested six people with terrorism-related offenses in raids today.

The U.K. terror alert was raised to “severe,” the second- highest level, in August as countries around the world expressed concerns that Islamic State militants may have returned to their home countries with plans to attack targets. Prime Minister David Cameron said the battle against Islamic extremism is a “generational struggle” that will probably last decades.

London police said last week when they arrested five people in a terror probe linked to yesterday’s raids. One of the men had traveled to Syria and may have had ties to Islamic State, the Times of London reported on Oct. 8.

Two Released

Two of the five men arrested last week were released while three remain in custody, the MPS in London said yesterday.

Thames Valley Police said they worked with officials in other agencies to detain three men and three woman in London’s Greenwich neighborhood, Portsmouth and Farnborough.

Thames Valley Police said that the arrests were in relation to conflicts overseas and weren’t linked to any immediate threat to the U.K.

A spokesman for the MPS declined to say whether there was a link between the two probes.

Britain joined the U.S.-led coalition of European and Arab allies carrying out military strikes against Islamic State positions in Iraq and Syria.