A number of Western countries have introduced extra measures to boost security after the London bombs.
Manhattan commuters will be affected
Passengers using the New York subway are to be subject to random searches, said city mayor Michael Bloomberg.
The Italian government approved a raft of measures, including surveillance of the internet and phone networks and making it easier to detain suspects.
France was on "red alert" and planned similar measures on video and phone surveillance, said the prime minister.
'Freedoms at risk'
Italy's cabinet approved the measures, first drawn up after the attacks on the UK capital two weeks ago. They include:
- doubling to 24 hours the time suspects can be kept in custody without charge
- interrogating suspects without lawyers present
- strengthening of measures to prevent terrorists from financing their operations
- compiling lists of mobile phone users to help police investigating suspected terrorist crime
- monitoring more closely immigrants from outside the EU who are already the subject of criminal investigations.
A special prosecutor will also be empowered to co-ordinate terrorism-related investigations, said Prime Minister Silvio Berlusconi.
Mr Berlusconi said the package would be submitted to parliament in the next few days and would get urgent treatment.
"The material was so delicate that it needed to be given a proper in-depth examination, given the fact that some of these measures risk limiting personal freedom," said the Italian prime minister.
His French counterpart said the government had taken "all measures necessary to ensure the safety of our fellow citizens".
"We also plan to strengthen a number of the systems we already have in place - this is the case for mobile telephony, for video surveillance," Dominique de Villepin said.
About 4.5 million people use the New York subway system every working day.
Mayor Michael Bloomberg said measures like the random searched were growing increasingly necessary.
But with more than 450 subway stations on the network, it is unclear whether the searches of passengers with bags or backpacks can be any more than a token deterrent, says the BBC's Jeremy Cooke.
Civil liberties groups have warned that random searches may be unconstitutional, our correspondent says.
But the New York police chief Ray Kelly has offered a guarantee that the searches will be truly random and that passengers will not be selected because of their apparent race or religion.
Meanwhile in Pakistan, calls for a nationwide protest against the arrest of hundreds of suspected Islamic militants in the wake of the 7 July attacks in London have received a muted response.
Only a few hundred supporters of opposition hardline Islamist parties turned out in main cities.
More than 200 people have been detained in recent days in a series of raids on mosques and Islamic schools, known as madrassas.