US president Barack Obama has commuted the sentence of an inmate who got a longer prison sentence because of a typo.

Ceasar Cantu, of Katy, Texas, is serving 15 years for trafficking marijuana and money laundering but the judge based the sentencing on a mistake in his pre-sentencing report which resulted in three and a half years' extra time. The typo occurred in the "offence level" - a numerical rating based on the severity of the crime and the defendant's sentence, among other factors. The pre-sentence report specified "36" when it should have been "34".

Cantu pleaded guilty in 2006 in federal court in Danville, Virginia. A judge ruled that because Cantu's lawyer did not object at sentencing, the court could not change it. The White House said it could only be rectified by the president. Cantu will now serve 11 and a half years. Mr Obama commuted only one sentence in his first term but has been using the power more in his second.