Kray must now return to jail to serve a 12-year sentence.

Three judges refused his application for leave to appeal against the conviction.

But Lord Justice Pill, sitting with Mr Justice Turner and Judge Rant, said Kray can challenge the length of the sentence.

Reggie Kray, at the funeral of his twin, Ronnie

The full hearing of his appeal against sentence will be heard later.

Kray, 72, of Sanderstead, south east London, was found guilty at Woolwich Crown Court last year of offering to supply cocaine to undercover police officers and also of supplying 2kg of the drug worth £63,500.

Former gangland torturer "Mad" Frankie Fraser and a host of other character witnesses insisted Kray was "too nice" to break the law.

But the prosecution told jurors how Kray - with accomplices Ronald Field, 49, and Robert Gould, 39 - were trapped by police officers posing as gangsters interested in drug-dealing.