Six men conspired to smuggle 69 Albanian migrants into the UK on a converted fishing boat stopped off the coast of Great Yarmouth in a "sophisticated" and "highly lucrative" operation, a court heard.

The near 30-metre-long trawler, called the Svanic, was intercepted by UK Border Force vessels late on November 17 last year and was escorted into Harwich.

Three men, described by the prosecution as crew members, were arrested when the boat reached land in the early hours of November 18.

Three more men, said to be "UK-based organisers", were subsequently arrested and all six were charged with conspiring to assist unlawful immigration between September 1, 2020 and November 30, 2020.

Five deny the charge and are on trial while one of the alleged "UK-based organisers" has admitted the offence.

Tony Badenoch QC, prosecuting, told a trial at Chelmsford Crown Court that after it was seized the Svanic was inspected and found to have been converted, with 19 sleeping berths.

He said the vessel was built in 1962 and it is not known when it was converted.

"On inspection the vessel displayed a multitude of faults," said Mr Badenoch.

"As an example, it only had a maximum lifesaving capacity of 20 persons.

"There were 69 migrants and three defendants on board and so there were plainly 20 lifejackets for 72."

He said that a "crossing of this kind in a vessel of this size is unusual".

The most common route for Albanian migrants entering the UK illegally from Belgium is in heavy goods vehicles, costing an estimated £2,000 to £3,000 per migrant, or in small boats such as Rigid Hull Inflatable Boats costing £2,000 to £4,100 per migrant, Mr Badenoch said.

"These methods are of fairly low sophistication," he said.

"Using a fishing vessel such as the Svanic is uncommon and more sophisticated.

"It requires the organisation to procure such a vessel, crew to skipper the boat, upfront fuel and mooring fees, as well as any other incidental payments for repairs and the like."

He said that migrants on the vessel were found to have hotel key cards on them, "suggestive of accommodation prior to the Svanic".

"The cost of a crossing of this kind is estimated to be circa £15,000 for each migrant," he said.

Arturas Jusas, 35, of Wandsworth Road, Lambeth, admitted at an earlier hearing to conspiring to assist unlawful immigration.

The court was played an audio file from a mobile phone from September 3 2020 in which Jusas said: "We're going to bring every week 50 people, yes, we need to invest now 40,000, if you want, 20 you, 20 me.

"From first trip we're going to get the money back."

Mr Badenoch said: "A single trip was therefore capable of returning 40,000 at the very least on the interpretation of that message."

He went on: "The unlawful moving of people in the manner alleged in this case is highly lucrative and it was for that purpose that the Svanic was being used."

He said that the Svanic was in the North Sea when it was intercepted.

"It was heading for the UK, it had on board 69 Albanian migrants," he said.

"No arrangements had been made to enter via the usual channels and in those circumstances the intentions of those involved are quite clear, to assist unlawful immigration."

The three men who were taken from the Svanic and arrested are Ukrainian nationals Igor Kosyi, 56, Volodymyr Mykhailov, 49 and Latvian national 44-year-old Aleksandrs Gulpe.

Kfir Ivgi, 39, of Corrigan Close, Finchley and Sergejs Kuliss, 32, of Albert Basin Way, Newham, London were subsequently arrested and are said by prosecutors to be "UK-based organisers".

The five defendants deny the charge against them.

The trial, estimated to last six to eight weeks, continues.