Prosecutors need to be brought into the 21st century, the director of public prosecutions has said, in the clearest statement yet of the need to reform the Crown Prosecution Service (CPS).

Writing in Guardian, Keir Starmer QC has outlined the need for "a greater emphasis on quality", warning that failure to modernise the system would lead to public dissatisfaction with the work of the CPS.

"The days of decisions being made by deskbound prosecutors behind closed doors are long gone," Starmer says. "Greater public scrutiny will also shine a powerful torch on some criminal justice issues that are ripe for reform."

Starmer singles out the outdated use of paper files and the need to be more open with the public as crucial areas of reform.

"We are still far too reliant on paper files, which ‑ all over England and Wales ‑ are shuttled on a daily basis between the police, prosecutors and courts in the back of vans," Starmer writes. "If a 21st-century prosecution service is to be delivered, the electronic file needs to be its main currency."

The publication today of new quality standards for the CPS comes after reports today that 4,000 suspected criminals failed to appear in court over the last three years because of problems with CPS files. The figure included 700 suspected violent offenders and 100 suspected sex offenders. The revelations, in the Sunday Express, come less than a month after a freedom of information request by BBC1's Panorama revealed almost 40,000 cases of violent assault were not prosecuted last year.

Starmer has already dealt with controversy surrounding decisions not to prosecute by publishing detailed reasons.

Last year, he explained why he was not prosecuting the family of 23-year old rugby player Daniel James, despite finding there was sufficient evidence that an offence of assisted suicide had taken place.

The DPP is drawing up guidelines for future cases of assisted suicide after a successful challenge by multiple sclerosis sufferer Debbie Purdy in the Lords.