It might be visited by 7 per cent of internet users every day, and have helped to win many a pub quiz, but Wikipedia is still hampered by its inability to guarantee that information appearing on the website is true.

To rectify this the online encyclopaedia is to tackle its reliability problem with a package designed to improve its trustworthiness and reliability.

The German-language version is to pioneer the first and potentially most controversial change, by which ordinary readers will lose their ability to alter any entry and see their changes appear instantly on the screen, New Scientist reports today.

Instead, instant editing will be restricted to a group of “trusted editors”, who must first earn their status by proving their commitment to the Wikipedia concept. One proposal is to limit trusted status to those who have made 30 reliable edits in 30 days. Ordinary users will still be able to propose changes, but these will have to be vetted by a trusted editor before they appear. The English-language version will retain instant editing for now.

Wikipedia has become immensely popular since it was set up in 2001. It includes more than two million entries in English and covers 252 languages. However, its unique structure, by which anybody can add, remove or edit information, is at once its strength and weakness.

While the “wiki” format, which takes its name from the Hawaiian word for “quick”, means it can draw on a vast pool of expertise from individuals all over the world, it is also vulnerable to deliberate abuse. Many companies and individuals are known to keep an eye on their own entries, inserting promotional material and removing potentially embarrassing details. More insidiously, some users engage in deliberate vandalism, deleting whole passages of text or inserting errors.

Serious errors, such as a defamatory allegation that an American journalist was involved in the assassination of President Kennedy, have sometimes gone unaltered for months. Though much loved by many, the site has developed a reputation for unreliability.

The drawbacks to the changes being implemented by the Wikimedia Foundation, the charity that runs the website, are that some users will be put off editing by the vetting process, and as the number of trusted editors is expected to reach about 2,000, there is likely to be a long wait before many bona fide changes are incorporated.

Readers will also be able to access an approved page that has been certified as vandal-free by trusted editors.

Another upgrade will involve the introduction of software that gives all editors a reliability rating, based on how their previous edits have performed. If information they post goes unchanged, they will be awarded high ratings, while if it is later edited by other users their ranking will slip. The software is designed by Luca de Alfaro, of the University of California, Santa Cruz.

Once ratings are compiled, the computer can give each chunk of text a reliability score, according to the editors who have changed it. Readers will be able to see this on a special page in which text will be darker when it is judged less likely to be reliable.

The main drawback, New Scientist says, will be that dedicated editors who correct vandalism may be penalised, as vandals often reedit their changes.