LONDON (REUTERS) - Britain will conduct a major counter-terrorism training exercise in October across parts of Scotland and northern England, Prime Minister Theresa May said on Monday (March 27), days after a lone attacker killed four people in London.

"The UK government considers national security across the whole of the UK as a top priority," Mrs May said in a statement.

"Training operations such as this one play a significant part in making sure police forces and other response agencies are able to fully draw on the latest intelligence and resources from the UK's security forces to protect against terrorism anywhere on our soil."

Such exercises take place regularly, the e-mailed statement from Mrs May's office said.

Four people were killed last Wednesday after British-born Khalid Masood ploughed his car into pedestrians on Westminster Bridge before stabbing an unarmed policeman at the British parliament building. He was later shot dead.