A tip off to led police to crack cocaine worth a street value of over £30,000 - and a dramatic ambush on the A19, on Teesside.

Several police cars were used to intercept a car as it reached the Crathorne Interchange, near Yarm, early today.

The two men inside, both from Thornaby, and aged 26 and 40 years respectively, were arrested.

They were forced to pull over in what Cleveland Police described as a "rolling stop check.''

As a result of that arrest officers from the Metropolitan Police arrested two men near Kings Cross in London and recovered several thousand pounds in cash.

All four men are helping police with their inquiries: the two Thornaby men at a police station on Teesside and the pair apprehended in London, are being held at Shoreditch Police Station.

Two Cleveland Police officers travelled south to interview the men detained in London.

The homes of the men stopped in the car on the A19 were searched by drugs officers.

Police said it was an "intelligence led'' operation.

Police Sergeant Jim Walton of Stockton Police's dedicated drugs unit said: "This is another significant recovery of Class 'A' drugs, removed from the streets of Stockton.

"It shows Cleveland Police are determined to continue to pursue the dealers of hard core drugs.''

* An Audi car was pulled over by police in Middlesbrough, in a separate operation on Tuesday night, and heroin worth £1,500 recovered. A 24-year-old local man was arrested and charged for being in possession of a Class 'A' drug with intent to supply.