The gunmen, described in court as 'loyalists', had allegedly been hired to kill John Dale, a dealer who was said to have 'ripped off' another man, who subsequently put a price of pounds 25,000 on Mr Dale's head.
Stuart Warne, who has admitted to being a link between the Ulstermen and the drug dealers, said that Patrick Doherty, who is alleged to have put the contract on Mr Dale, told him that there were 'other hits in the pipeline'.
Mr Doherty, 35, of Brockley, south London, and George McMahon, 46, of New Cross, south London, are both alleged to have conspired to supply cannabis. Also in the dock are Terence McCrory, 30, of Belfast, and John Green, 32, of Falkirk, Scotland, who are alleged to have been the gunmen. All four are charged with others with conspiring to murder Mr Dale. Mr McCrory, Mr Green and Mr Doherty are charged with others with conspiring to murder David Norris, a police informer. All the charges are denied.
Warne, who is serving a life sentence after admitting conspiracy to murder and drug charges, gave evidence flanked by two detectives. He told the jury that Mr Doherty said he was prepared to pay pounds 35,000 to have Mr Norris killed and claimed Mr Norris had 'grassed up a number of firms', including telling police about a warehouse containing drugs in Greenwich, south London.
Timothy Langdale QC, for the prosecution, asked Warne if Mr Doherty had specified how many other killings might be required. 'He said five or six after that,' Warne said. But no more names were given.
He described a meeting with Mr Doherty in a south London public house when Mr Doherty used his mobile telephone to order pounds 20,000 in cash to pay for the Dale killing; it arrived 30 minutes later, accompanied by an armed guard.
Warne said that he was told by Stephen Pollock, a Kent-based Irish drugs dealer, how Mr McCrory and Mr Green planned to kill Mr Dale. 'They were going to cosh Dale and carve his heart out because there were others in the pipeline. They wanted to do the first one and make an announcement.'
The two men failed to kill Mr Dale because he was using evasive tactics and were annoyed because they had been given incorrect addresses. Eventually, Renwick Dennison, another Irishman, who has also pleaded guilty to conspiracy to murder, shot him.
When Warne told Mr Doherty that the hit had taken place, he allegedly replied that he wanted proof that Mr Dale had been attacked by the Irishmen.
Warne told the court that after the Irishmen learnt that Mr Dale had survived and was in hospital, they said they suspected he had been wearing bullet-proof clothing and asked for a high-velocity gun. 'They said they would do him in the hospital,' he said.
The case continues today.