Crime boss Willem Holleeder has denied ordering the assassination of a property investor and drug dealer whom he extorted for €1 million, during the latest stage of his long-running murder trial.

Kees Houtman owed Holleeder the money in a dispute that began when the pair clashed over how to invest drugs money in business premises in Amsterdam-Noord. He was shot dead on his 46th birthday outside his home in Osdorp, in November 2005.

Holleeder was convicted and served a jail sentence for extortion relating to his dealings with Houtman, but insisted on his innocence when the episode was raised during his trial.

‘I don’t want to talk about the extortion case any more because I’ve served my sentence,’ he said. ‘I’m here now because I’m accused of an assassination.’

The prosecution says the extortion case was the basis of a feud that led Holleeder to order both Houtman and bar owner Thomas van der Bijl to be killed. The 59-year-old is accused of ordering or being involved in the deaths of six underworld figures, including his brother-in-law and old school friend Cor van Hout.

Holleeder said he got to know Houtman in 1992 when the two men lived in the same block of flats in Spain. ‘We had a beer together sometimes, that was it. A nice, friendly guy. I knew he was involved in hash. I don’t know why he was murdered, but I had nothing to do with it anyway.’

Witnesses including Holleeder’s sister Astrid and gangland figure Peter la Serpe said Holleeder issued instructions to murder three associates including Houtman and Van der Bijl with the words ‘Osdorp first’, referring to Houtman’s home district. He is also said to have agreed to pay the killers €65,000. Holleeder says no such meeting ever took place.

In the high-security courtroom known as ‘The Bunker’, Holleeder said he was the victim of a conspiracy orchestrated by Astrid to put him behind bars. He claimed the accounts of paying assassins to dispose of his associates were ‘stories’ put about by another gangster, John Mieremet. Mieremet, who was killed in Thailand on the same day as Houtman, was also allegedly killed on Holleeder’s orders.

Houtman’s widow, Maria, noted that that her husband was one of three men who had once been friends with Holleeder, all of whom were now dead. ‘Now there’s only one left.’

Holleeder replied: ‘All these stories came from John Mieremet… Kees Houtman undoubtedly told his wife. Kees Houtman also told these things to Thomas van der Bijl. All these things originated with John Mieremet.’

He said Houtman was not in dispute with him but with George van Kleef, another career criminal who was murdered in 2005, about cannabis trafficking.

Earlier in the day the judges rejected an application by Holleeder’s lawyers to release him from the remand prison where he is being held during the trial on the basis that the evidence against him was not strong enough. It follows the acquittal of three of the four men who were accused of carrying out the murder of real estate investor Willem Endstra, allegedly on Holleeder’s orders. The fourth is no longer alive.

Read our feature: The hottest ticket in Amsterdam is a seat at the Holleeder trial