A police helicopter and dog unit was called out last night after reports of suspicious activity.

Hertfordshire Constabulary were called at 2.31am this morning to investigate three men acting suspiciously in Kingswood Road, Watford.

Officers searched the area with the help of the National Police Air Service and the Bedfordshire, Cambridge and Hertfordshire dog unit.

No suspects were found but the enquiry continues.

Witnesses who saw anything suspicious who have not already spoken to the police are asked to call 101 and quote ISR 39 June 23.