The brother of a city high-flier who died after an unprovoked attack more than 15 years ago claims significant facts from the investigation were kept from his family by police.

Michael Abatan says he can no longer trust Sussex Police after discovering a serving officer was with a group of people who allegedly attacked his brother Jay Abatan outside a Brighton nightclub in January 1999.

The 42-year-old tax specialist from Eastbourne was assaulted while waiting for a taxi outside the now closed Ocean Rooms with his brother Michael.

The father of two, who worked for PricewaterhouseCoopers, hit his head on the pavement, suffered a fractured skull and died in hospital five days later.

Two men, Graham Curtis and Peter Bell, were arrested by Sussex Police within 24 hours of the attack but manslaughter charges were later dropped.

Michael Abatan will meet Sussex Police and crime commissioner Katy Bourne in Lewes tomorrow to discuss the lack of progress of the investigation.

Complaints from Jay Abatan's family about Sussex Police's failings in the initial investigation led to separate reviews by Essex, and Avon and Somerset police forces.

Michael Abatan says he believes police links with his brother's alleged killers have always made it impossible for Sussex Police to get justice for Jay.

He said there had been "a wall of silence around the case" and that he would not rest until he was told "why his brother was denied justice".

In October 2010, Brighton and Hove Coroner Veronica Hamilton-Deeley recorded a verdict of unlawful killing.

Mr Bell gave evidence saying he had not seen Mr Curtis hit or kick Jay Abatan, but he declined to answer when he was asked if he had done so himself.

Mr Curtis hanged himself at his Brighton home in June 2003.

Michael Abatan said: "My family can no longer trust Sussex Police.

"We cannot understand why such significant facts have been kept from us regarding the night my brother was attacked.

"Important material such as this should have been fully disclosed to us, Essex and Avon and Somerset forces and also to the public.

"I was led to believe that Sussex Police would be 'open'.

"The revelation that a police officer was with the group on the night that they attacked my brother and I makes the handling of this case all the more reprehensible."

Michael Abatan said his brother's case was the only non-white murder that year in Sussex and claims it was "the only one not to be given adequate homicide resources".

He said: "We were treated like second class citizens, just as the (Stephen) Lawrence Inquiry was reporting on institutional racism in the police.

"Given the catalogue of flaws we have been subjected to, this merits a full public inquiry into the case and I will be taking this up with the Home Secretary.

"The death of Stephen Lawrence and the subsequent report by Sir William Macpherson that labelled the Metropolitan Police force "institutionally racist" ushered in sweeping reforms.

"It is clear that those reforms were not implemented in Jay's initial investigation."