UPDATE:  Police have confirmed that they are no longer treating the incident as terror related.

Armed police intercepted a coach on the M6 toll road near Lichfield, as part of a counter-terror operation this morning [Thurs]. The bus was stopped on the hard shoulder between junctions T3 and T4 at the Weeford Park Plaza.

West Midlands Police were concerned about an item on board the coach, and the passengers were evacuated. The motorway was shut in both directions, including the M6 toll, as the incident was dealt with.

Eyewitnesses reported seeing bomb disposal units passing the queue at the toll, and 'armed police everywhere'.

The incident on the M6 toll road is not being linked with the arrests this morning also part of a counter-terrorism operation.

Sources say a man was seen pouring liquid into bag which was smoking. A journalist at the scene reported being asked to move away. 

Police interviewed passengers who were on the coach, which has been confirmed as Mega Bus en route from Preston to London with 48 passengers on board. 

Police reportedly told a man stood outside of his car in the queue to get inside, close windows and use air conditioning. However, police have said that the incident is not a chemical spill.

[Map shows the approximate location of the coach]