David Cameron has said "life should mean life" as the government considers US-style 100-year prison sentences for murderers and serious offenders.
The prime minister's comments come as the Conservatives consider alternatives to "whole-life" sentences.
The government is looking at the plan after a European court ruled in 2013 that such sentences breached the European Convention on Human Rights.
The 100-year terms would allow sentence reviews, satisfying the court.
The proposed change in sentencing regulations for England and Wales comes as Conservative ministers prepare to publish reforms to the UK's human rights laws.
They want Britain's Supreme Court to have the final say in cases relating to human rights, rather than the European Court of Human Rights (ECHR) in Strasbourg.
The ECHR ruled in July that whole-life sentences - allowed under English law - breached the European Convention on Human Rights because they did not include the possibility of a "right to review".
The government was given six months to respond to the decision, which Mr Cameron has said he "profoundly disagreed" with.
He told the BBC on Thursday: "There are some people who commit such dreadful crimes that they should be sent to prison.
"Life should mean life and whatever the European Court has said we must put in place arrangements to make sure that can continue."
One option now being considered by the government is a plan to allow judges to impose jail terms of hundreds of years, which would potentially allow offenders to have their sentences reviewed and reduced.
Policing minister Damian Green, who leads the committee responsible for drawing up reforms to limit the influence of the Strasbourg court on British life, told The Daily Telegraph: "British laws must be made in Britain. I want to restore the respectability of human rights."
The Prison Reform Trust's Juliet Lyon said the government was trying to "dodge complying with the Human Rights Act".
"It sounds like a dangerous nonsense," she said. "What it risks is further inflation in sentencing. People serving life sentences are serving three years longer than they did 10 years ago."
Human rights barrister Geoffrey Robertson QC said that sentencing people to hundreds of years of imprisonment was a "cruel and unusual punishment", and was contrary to the English Bill of Rights of 1689.
"There is a place for mercy," he added.
The government's move comes as the killers of murdered British soldier Lee Rigby, who was hacked to death outside Woolwich barracks in south-east London in May last year, await sentencing.
Mr Justice Sweeney said he would pass sentence on Michael Adebolajo, 29, and Michael Adebowale, 22, after a key Appeal Court ruling on the use of whole life terms later in January.
There are currently 52 criminals in England and Wales serving whole-life prison terms.
Elsewhere, Mark Bridger, 47, who was sentenced to life in prison in May for the murder of five-year-old Welsh schoolgirl April Jones, has lodged an application to appeal against his sentence.
His initial hearing at the Court of Appeal is scheduled for early 2014.
Ian McLoughlin, 55, who admitted killing Good Samaritan Graham Buck, 66, in Hertfordshire, while on prison day-release, was given a 40-year sentence in October.
Mr Justice Sweeney, who sentenced McLoughlin at the Old Bailey, said he was barred from passing a whole-life tariff because of the European judgment.
Attorney General Dominic Grieve is due to appeal against his sentence, describing it as "unduly lenient".
On the day of McLoughlin's sentencing, Justice Secretary Chris Grayling said whole-life tariffs should be available for "the most serious offenders".
"That is the position clearly stated in our law, and what the public expects. The domestic law on this has not changed."
Lawyers at the Ministry of Justice have confirmed they are looking at whether the law needs to be changed to allow judges to hand down more severe sentences.
Under the US system, very long prison sentences are often imposed by states as an alternative to the death penalty.
In August last year, Ariel Castro, who abducted three women and held them captive for more than a decade, was sentenced to life imprisonment without the possibility of parole, plus 1,000 years.
He was found hanged in his cell in Ohio in September.