LONDON (Reuters) - Part of Britain s M1 motorway was closed on Tuesday after what police described as a suspicious object which appeared to be  some form of chemical  was found under a bridge. The object was discovered at around 0630 GMT and prompted police to close the motorway in both directions between Milton Keynes and Northampton in central England. Thames Valley Police said bomb disposal experts had examined the object and found it had no explosive element.  However chemical analysis is ongoing on the object to ascertain what the object might be but it appears to be some form of chemical,  police said. Photographs on social media showed long queues on the motorway, one of Britain s main road arteries between London and the north.  Police said they were working to divert motorists away from the scene and to move those who had been stuck on the carriageway. They appealed to drivers to avoid the area. 