Magistrates are being advised by the courts service to disregard normal sentencing guidelines when dealing with those convicted of offences committed in the context of last week's riots.

The advice, given in open court by justices' clerks, will result in cases that would usually be disposed of in magistrates courts being referred to the crown court for more severe punishment.

It may explain why some of those convicted have received punitive sentences for offences that might normally attract a far shorter term.

In Manchester a mother of two, Ursula Nevin, was jailed for five months for receiving a pair of shorts given to her after they had been looted from a city centre store. In Brixton, south London, a 23-year-old student was jailed for six months for stealing £3.50 worth of water bottles from a supermarket.

The Crown Prosecution Service also issued guidance to prosecutors on Monday, effectively calling for juveniles found guilty of riot-related crimes to be named and shamed. Those dealt with in youth courts are normally not identified. The youngest suspects bought before the courts last week in connection with the riots were an 11-year-old girl and a 12-year-old boy.

The sentencing advice from Her Majesty's Courts and Tribunals Service came to light after the chair of Camberwell Green magistrates court, Novello Noades, claimed that the court had been given a government "directive" that anyone involved in the rioting be given a custodial sentence. She later retracted her statement and said she was mortified to have used the term "directive".

Clarifying what had occurred, HMCTS explained that a senior clerk had circulated instructions to court clerks that they should advise magistrates to consider disregarding normal sentencing guidelines.

"Sentencing is a matter for the independent judiciary," it said. "Under the Criminal Procedure Rules justices' clerks and legal advisers in magistrates courts have a responsibility to give advice to magistrates on sentencing guidelines.

"All advice is given in open court and the parties are entitled to comment. Accordingly magistrates in London are being advised by their legal advisers to consider whether their powers of punishment are sufficient in dealing with some cases arising from the recent disorder.

"Magistrates are independent and not subject to direction from their legal advisers."

The advice was issued last week in the aftermath of the riots. It was given, it is said, to ensure consistency of sentencing across the country. Courts can therefore consider the riots as an aggravating factor in any offence, making stealing from looted shops more serious than conventional shoplifting.

Last week David Cameron told the recalled House of Commons that anyone involved in violent disorder should expect to go to prison. The Ministry of Justice denied that it had asked the HMCTS to issue the advice.

The Judicial Communications Office, which issues statements on behalf of judges, also dismissed suggestions it had been involved. "The senior judiciary has given no directive in relation to sentencing for offences committed during the recent widespread public disorder," it said.

"When passing sentences judges consider many factors, including the punishment of offenders, the reduction of crime by deterrence, and the need to protect the public."

Magistrates can only sentence offenders to up to six months in prison for a single offence. The chairman of the Magistrates' Association, John Thornhill, has been pressing the government to raise the maximum sentencing power of magistrates to 12 months.

"Many of these cases would have been dealt with more expeditiously and cheaper if we had the 12-month sentencing powers," Thornhill said. "They would not have needed to be sent to the crown courts."

In its advice on identifying youths, the CPS said: "We have issued guidance to prosecutors that states they should ask the court to lift the anonymity of a youth defendant when they believe it is required in the public interest that the youth be identified. Legislation permits the court to do so after conviction. These representations will be made on a case-by-case basis."

Among the criteria the court should consider when identifying any juvenile is whether the move is "necessary, proportionate and there must be a pressing social need for it".

Among those appearing before City of Westminster magistrates court on Monday was Wilson Unses Garcia, 42, of Walworth, south London. He was jailed for six months for receiving stolen property: two tennis racquets worth £340 looted from a sports shop in south London. When police searched his property they found the racquets still in wrapping and with price labels on them.

Garcia said he had had the racquets for some time. Police said he later told them: "I knew it was not right the minute they put them into my hand."

His solicitor told the court that Garcia, who pleaded guilty, had not participated in looting, did not agree with the rioting and had accepted the racquets from a man he knew only from his first name as payment of a £20 debt.A pregnant woman accused of hoarding £10,000 of electronic equipment looted during the London riots has been remanded in custody ahead of her trial.

Alicia Wilkinson, 22, was discovered with a vast amount of stolen guitars, televisions and hair braiding equipment when police raided her home in Outram Road, Croydon, at the weekend.

The Gatwick airport worker, who is due to give birth in four months, was denied bail after pleading not guilty to handling stolen goods at Croydon magistrates court.

Robert Simpson, prosecuting, told the court the flat was "noticeably packed" with the equipment, much of which had been looted from Croydon electronics store Richer Sounds at the peak of the chaos on 8 August.

Wilkinson claims she returned from housesitting for her mother to find the flat she shares with boyfriend Nick Cuffy and his brother Neil was full of the haul, the court heard.

Her defence solicitor told district judge Robert Hunter she was a "highly unlikely defendant", adding it had "played on her mind ever since then about the right course of action to take".