Three times as many Tube trains are running through red signals than 10 years ago, it has been claimed.
In 1995 there were 296 signals passed at danger (Spads) but in 2004 it rose to 969, which the London Assembly's Lib Dems says points to "complacency".
London Underground (LU) said it has an automated system to stop trains should they accidentally pass a red signal.
But Lib Dem transport spokesman Geoff Pope said passengers would worry that a technical hitch could cause a crash.
He added: "The failure to tackle the spiralling number of Spads smacks of a history of deep malaise and complacency over many years from LU."
"Serious questions must be asked into how, over years, LU has failed to deal with the ever-increasing number of Spads.
"While the Tube does have comprehensive safety systems, passengers will worry that a technical failure might lead to a collision and loss of life."
In 2000, 31 people died at Ladbroke Grove when two trains collided after a newly-employed Thames Train driver mistakenly ran through a stop signal.
But LU said Spads do not pose the same risk on the Underground, because of its Automatic Train Protection (ATP) which stops over-running trains.
A spokesman said: "Safety is our top priority. The Tube is equipped with Automatic Train Protection so if a train does inadvertently pass a signal at danger it will be brought to an immediate halt.
"Driver training is kept under constant review and we work closely with the infrastructure companies, Tube Lines and Metronet, to improve safety and keep the Underground as safe as possible."
The busiest Tube line, the Northern Line, closed for several days last month, when drivers walked out because the emergency brakes kept failing.