A charity director, who was jailed for five years for allowing heroin to be supplied at a homeless hostel she ran, has been refused leave to appeal against her conviction.

Ruth Wyner can only appeal against the length of her sentence, a High Court Judge has ruled.

Wyner, 49, who was head of the Winter Comfort homeless charity in Cambridge, was jailed in December after being convicted of allowing heroin to be supplied at the hostel.

One of Wyner's managers, John Brock, 49, was jailed for four years after being convicted of the same offence.

He was also given leave to appeal against his sentence but not against his conviction.

The judge announced his decision in a letter to Wyner's lawyers following a hearing in London last week.

After the decision, a spokesman for the Winter Comfort charity expressed his dismay.

He said: "We are very, very disappointed by this ruling because we feel that their convictions are wrong - although we obviously welcome the granting of leave to appeal against sentence."

Supporters of Wyner and Brock, known as the Cambridge Two, have launched a campaign aimed at getting them released.

At their trial at Kings Lynn Crown Court last year, the key issue was whether Wyner and Brock had a duty to inform on hostel residents they knew to be dealing in drugs.

Both argued that their duty to confidentiality to clients outweighed that.

But police said the Cambridge hostel had become a centre for drug dealing and that Wyner and Brock had knowingly turned a blind eye.

Winter Comfort officials said the decision could have wide implications for people working with the homeless and with drug addicts.