Three men involved in a multimillion pound drug smuggling operation on a scale described as "far beyond the norm" have been jailed for more than 36 years.

Bas Van Der Weijden, Romeo Apostu and Zahid Mahmood were all said to have played a significant role in the "imaginative and professional" enterprise in which massive quantities of heroin and cocaine were hidden inside car battery starter packs transferred from Holland to an industrial unit in Northfleet.

The operation was smashed by police surveillance officers when they discovered 40kg of heroin and 2kg of cocaine, with an estimated street value in excess of £4million, in four suitcases in the area on March 5.

One was in the boot of a car being carried on a recovery truck driven by Mahmood in Springhead Road. It contained 10kg of heroin of 68% purity.

The other three cases were found in a Skoda Fabia belonging to Van Der Weijden in the car park of Ye Olde Leather Bottle pub in Dover Road.

They contained 48 packages of heroin of 51 to 68% purity, and two packages of cocaine of 79% purity.

Van Der Weijden, from Eindhoven in the Netherlands, and Apostu had checked into the nearby Granby Hotel just hours earlier, having flown into London City Airport from Amsterdam the day before.

Records showed that in the six months previous the two men had booked a twin room at the hotel on 14 occasions, usually just a fortnight apart and lasting a few days.

The trip on March 5 was their 18th visit to the UK.

Van Der Weijden was arrested in the pub car park just minutes after surveillance officers had seen him hand over the suitcase to Mahmood at a rendezvous point in Dover Road.

The court heard a shop receipt found in his possession were for two of the Dunlop trolley cases which had been bought less than two hours earlier at the Sports Direct store in the St George's Centre, Gravesend.

Apostu was arrested at the hotel.

Passing sentence on Friday, Judge Julian Smith said that although there was insufficient evidence to suggest Van Der Weijden and Apostu's earlier visits also related to the supply of drugs and in similar quantities, it would be an "astonishing situation" if they were.

Van Der Weijden, 41, admitted two offences of supplying class A drugs and was jailed for 14 years. Apostu, 44, a Romanian national but with no fixed address, admitted the same charges and was jailed for 13 years.

Father-of-six Mahmood, 43, from Handsworth in Birmingham, admitted supplying heroin, as well as possessing heroin with intent to supply in relation to a further 1.45kg of heroin with a street value of £200,000 found in a safe at his home.

He was jailed for a total of nine years and four months.

Judge Smith told them: "This was drugs offending of the gravest kind. Each of you has admitted you were involved in the supply of class A drugs on a considerable scale and a scale far beyond the norm."

The judge also remarked that he could only sentence them on the basis of the quantities of drugs they were caught with, but added: "It would be naive and misrepresent the evidence, and possibly an affront to common sense, if I was to approach this case in any other way than it being an organised, professional and on-going enterprise."

The court heard the drugs were smuggled from Holland into the UK using a rotation system.

Prosecutor Anthony Prosser said they were hidden within hollowed-out car batteries, with the lead-lined cavity created enabling them to avoid detection by scanners at customs.

Once in the UK the car parts would be delivered to the business unit in Northfleet, the drugs removed and repackaged for onward distribution, while the car batteries would be re-assembled and then returned to Holland for re-use.

Mr Prosser said the amount of drugs the three defendants were involved with on that day was "a lorry load".

"The Crown's case is that all were involved in a significant role, motivated by financial gain and an understanding of the scale of the operation," he added.