Almost two-thirds of rape charges brought before Scottish courts for trial in 2008/09 did not result in a conviction, new figures reveal.
The latest statistics on rape charges, published in a report by the Crown Office, show 62% of charges indicted for trial did not lead to conviction while 32% resulted in a conviction for rape or a similar offence.
According to the statistics, the remaining 6% of cases have not been concluded yet.
The figures represent a fall on the previous year 2007/08 when 36% led to convictions.
The report also revealed the number of charges of rape reported to the Procurator Fiscal in 2008/09 was 528, a fall of 18% from 647 in 2007/08. Of the 2008/09 charges, 34% were indicted for trial.
The Crown Office said the figures pre-date changes made in May 2009 to improve the way in which sexual offences are investigated and prosecuted.
The National Sexual Crimes Unit now leads the prosecution of the most serious sexual offences, including rape and sexually-motivated murder. The unit is made up of a team of specialist prosecutors and a dedicated team of specialist procurators fiscal.
Justice Secretary Kenny MacAskill said: "Rape is a horrific crime and we want to ensure that those that commit it are caught and victims are given justice.
"Last year we brought in the Sexual Offences Act, which brought greater clarity to the prosecution of sexual crimes, but more can be done to improve the conviction rate.
"We want to remove the obstacles that occur in so many cases. That is why we will explore how we can make sure juries will not be able to take into account any perceived delay in reporting rape or any apparent lack of resistance from the alleged victim when reaching their decisions.
"I have also asked Lord Carloway to carry out a review of Scots criminal law, which will include examining the principle of corroboration, which is a key issue in many rape cases brought before the courts."
The Sexual Offences (Scotland) Act brought in a legal definition of consent and allows one party to withdraw it at any stage, whether they initially gave consent or not.