The London Assembly has been told that 70% of the Metropolitan Police's technology platforms are "obsolete".
The Assembly was told some Met officers are still using desktop computers that take more than half an hour to log on to, "as a result of a failure to develop a long-term IT strategy".
Speaking at a meeting of the Assembly's Budget and Performance Committee, Met assistant commissioner Mark Rowley warned that close to 70% of the Met's technology platforms are currently obsolete, and that he expected this figure to rise to 90% by 2016.
He went on to admit that the force's technology was "not in a good place" and that more than 400 separate IT systems are currently in use, with some dating back to the 1970s.
He also gave an example of how officers recording a crime may have to enter the name of suspects and witnesses more than 12 times on separate systems, and said that the 20,000 plus new mobile devices the Met wants to use to streamline the process will take another two years to deliver.
Faith Boardman, non-executive adviser in the Mayor's Office for Policing and Crime, added that the Met "simply did not possess a long-term IT strategy". She said that the force was now "reaping the rewards" of a "failure to look at technology in the round".
The Budget and Performance Committee is currently reviewing how the Met can improve its use of technology while cutting ICT spending by £42 million in 2014-15, and a further £60 million in 2015-16.
John Biggs, London assembly member, and chair of the Budget and Performance Committee, said: "It is shocking that some police officers in London are forced to wait more than 30 minutes just to turn on a desktop computer. The public want to see officers on the street tackling crime, not struggling with antique technology back at the station."
Biggs said: "The Met cannot afford to go on like this. Its forthcoming strategy [expected to be delivered this summer] must address these problems while focusing on the potential that new technology offers, to drive down costs while increasing productivity and boosting public confidence."