Sri Lanka's cabinet has announced sweeping anti-terror measures after months of worsening violence between security forces and Tamil Tiger rebels.
Neither side has formally declared a return to hostilities
Ministers stopped short of banning the rebels but tightened existing emergency laws which have been dormant since a 2002 ceasefire that is now in shreds.
Security forces will have wide-ranging powers to search, arrest and question.
Last week the rebels said the truce was defunct. They have yet to respond to Wednesday's cabinet announcement.
More than 3,400 people have been killed in Sri Lanka since late last year, the authorities say.
The government said the far-reaching measures, which do not mention the Tamil Tigers by name, would take effect immediately.
Wearing a uniform "relating to terrorism" or assisting or harbouring anyone "engaged in terrorism" will be prohibited under the new regulations, a statement said.
Taking part in "any activity relating to terrorism" is also banned, as is any financial or other support to a person or group deemed to be engaged in "terrorist-related activities".
"Contravention of these regulations carries penalties imposed by a high court, varying from imprisonment from 10 to 20 years, or five to 10 years, depending on the nature of the offence," the statement said.
Foreign Minister Mangala Samaraweera said Sri Lanka's ban on the rebels had not been reimposed because a similar move in 1998 had failed to end violence.
Observers say Wednesday's announcement is aimed at appearing tough while not closing the door on negotiations with the rebels.
The rebels say they have no option but to push for independence
The government is under pressure following months of bloodshed.
The pro-rebel TamilNet website said the cabinet decision was "a major breach" of the truce accord and gave "excessive powers of arrest and detention to the Sri Lankan armed forces".
It recalled that "thousands of Tamil men, women and children were indiscriminately arrested, tortured and detained for indefinite periods" until previous anti-terror laws were suspended as part of peace moves.
Sri Lanka's government lifted its ban on the Tamil Tigers ahead of the ceasefire deal and peace talks brokered by Norway.
The old Prevention of Terrorism Act was effectively suspended following the truce.
The government said on Sunday its relationship with the rebels was under review.
Two days earlier President Mahinda Rajapakse's brother, Gothabaya, survived a suicide bomb attack in Colombo, for which the rebels were blamed. The rebels remain proscribed as terrorists by countries such as the US, the UK, Canada, India and across the European Union.
They are fighting for independence for minority Tamils in the north and east of Sri Lanka. About 65,000 lives have been lost since 1972.