Police have said the criminals were part of a "large, very sophisticated, international organised crime gang."

The multi-agency investigation began in November 2007.

A complex web of family members and criminal associates in both Kent and Teesside underpinned the large-scale drugs enterprise that also included money laundering and mortgage fraud.

Since the investigation began 31 men and women have been charged - nearly half of them from Kent - and today's sentencing brings the trial phase of the investigation to an end.

Sixteen people have been sentenced to a total of 70 years and one month in jail.

Head of Major Crime at Kent Police, Detective Superintendent Tim Smith, said: 'It's hugely rewarding to see these tangible results after such a long, complicated and multi faceted investigation.

Audio: Head of Major Crime at Kent Police, Det Supt Tim Smith, talks to KentOnline

"We've taken out the ringleaders of a very organised and dangerous crime gang whose members stopped at nothing to fuel their greed for money and the high life through the illegal drugs trade.

"But they seriously underestimated the determination and resources of Kent Police and the other law enforcement agencies that worked with us both in the UK and overseas.

"Our work isn't over because we're pursuing the gang's money and assets but today's sentences mean we've broken the back of what has been one of the biggest operations ever led by Kent Police.

"But the most satisfying thing of all is that we have saved some people from certain death and enhanced the quality of life of others by taking these gang members out of the community and allowing the criminal justice system to punish them."

The investigation peaked last November when 270 enforcement officers and detectives from Kent, Teesside and London arrested 31 people and searched 50 residential, commercial and rural locations. Among the many items they seized were:

• £262,000.00 in cash
• Six kilos of almost pure cocaine (£500,000)
• Threetonnes of cannabis (£2.5 million)
• 22 kilos of amphetamine sulphate (£1 million)
• 4130 ecstasy tablets (£20,000)
• Onekilo of crystal MDMA (£25,000)
• Two handguns (one linked to an attempted murder)

Head of Crime Operations for Cleveland Police, Detective Chief Superintendent Mark Braithwaite, said: 'Organised drug cartels wreak massive harm on vulnerable individuals, on families and on communities both in Teesside and elsewhere.

"The higher level players are greedy, very often violent and devoid of social conscience. All they are bothered about is making a fast buck on the back of other people's misery."

Kent Police is now actively pursuing the gang's money and assets through the legal system so that the proceeds of their criminal activity can be ploughed back into fighting crime. So far £2.375 million has been confiscated.