'Huge steps forward' on Tube since 7/7 London bombings
London Underground (LU) has said it has taken "huge steps forward" to improve safety on the Tube since the bombings exactly five years ago.
LU managing director Mike Brown said: "The Tube is safe" on the anniversary.
But he added: "Like any open transport system network, where you don't search everyone going on to the system there will be possibilities for people."
Digital systems, increased emergency training and more CCTV cameras have been introduced on the network.
Four suicide bombers detonated explosives on board three Tube trains and a bus during the morning rush hour on 7 July 2005.
After the attacks, the radio systems were heavily criticised because emergency teams and Tube workers were unable to talk to each other when they were in the tunnels.
A digital radio system, called Connect, was installed on the entire network in 2008, to replace the old analogue radio and transmission systems.
Another digital radio system called Airwave, which uses the same technology as the Connect system, rolled out in 2009, and is used on the Tube by the Metropolitan Police Service (MPS) British Transport Police (BTP) and the City of London Police.
"We have taken huge steps forward in the time since the 7 July bombings," said Mr Brown.
"I believe we have as many of the mitigation factors in place as we can to reduce the potential for the reassurance of these horrendous events.
"We've increased hugely the number of CCTV cameras across the network. We have more cameras across our Tube system than any other subway in the world."
Since 2005, the number of CCTV cameras on the Tube have been increased from 8,500 to 12,000.