Liberal Democrats have called for millions of pounds earmarked to extend the London congestion charge to be spent on improving security in the city instead.
Plans to install mobile telephone access across the Tube network must also be reassessed because phone signals can be used to trigger bombs, the party's London Assembly members said.
Both ideas were put forward in a ten-point plan to help protect the capital against further terrorist atrocities.
Five weeks before the July 7 bombings, Transport for London (TfL) announced plans to introduce mobile phone transmitters in all 270 London Underground stations within three years, with expansion into all tunnels from 2008.
However, the signals can be used to remotely detonate bombs.
The March 2004 Madrid atrocities which killed nearly 200 used mobile phones, although these were detonated by the phones' alarm functions rather than by a signal.
TfL is pressing ahead with the plans, which are expected to bring in tens of millions of pounds from mobile phone operators, despite the terror strikes on the transport network.
Lib Dem London Assembly leader Graham Tope said: "Why introduce another terrorism risk to the transport network at this time?
"If they are going ahead regardless without reviewing it I think that is stupidly irresponsible."
The Lib Dems also suggested there should be police boxes at all mainline stations which would be permanently staffed during rush hour.
And in a further controversial proposal, they suggested merging British Transport Police's London division with the Metropolitan Police to improve co-ordination and communication.
The Assembly members said a £55 million investment in security could be paid for by scrapping the proposed westward extension of the congestion charge.