Downing Street has sought to play down reports of a rift with the Liberal Democrats over new counter-terrorism measures set to be announced.
No 10 said David Cameron would set out an agreed government position in his statement to the House of Commons.
Its focus would be on “targeted” action to protect the UK and counter threats from Islamic extremists, it added.
Some Tories have urged new powers to seize passports from returning fighters but Lib Dems have urged caution.
The strengthened anti-terror response, to be announced at 15:30 BST, follows increasing violence in Iraq and Syria and concerns about British fighters returning from the countries.
The prime minister and his Lib Dem deputy Nick Clegg were locked in talks over the weekend after the UK’s terror threat level was raised to “severe” from “substantial” on Friday.
The Conservatives have proposed new laws to seize passports and impose temporary bans on fighters travelling home from foreign conflicts.
Under the proposals, UK nationals suspected of being involved in terror acts would be allowed to keep their British citizenship, but they would be prevented from re-entering the UK for a period of time.
However, the Liberal Democrats have questioned the legality of such measures. Former party leader Sir Menzies Campbell said rendering citizens stateless was regarded as illegal in international law.
The Lib Dems have said they would only agree to policies that were made calmly, on the basis of evidence and that maintained the liberty of British citizens.
At the daily briefing for journalists, Downing Street described the negotiations with the Lib Dems – which are understood to be continuing – as “normal”.
A No 10 spokesman declined to confirm whether Mr Cameron would announce new legislation, saying there would be a range of measures which could be put in place in a variety of ways.
Labour and the police have called for the return of powers that would allow authorities to put jihadists under closer surveillance and to disrupt their travel plans.
They want the government to consider the case for re-introducing control orders – which were scrapped in 2011 – or to beef up the existing terrorism prevention and investigation measures which replaced them.
It is already a criminal offence to travel abroad to commit or prepare a terrorist offence or to travel for the purpose of terrorist training, with suspects able to be prosecuted in the UK.
Clive Coleman, BBC Legal Affairs Correspondent
There is a real and important difference between removing a person’s citizenship and removing their passport.
If a British citizen who holds sole British nationality – ie does not have dual citizenship – has his or her British citizenship removed, that would render the person stateless, and that is contrary to both international and domestic law. Under current law, the home secretary is prevented from removing citizenship if to do so would render a citizen stateless.
So, in practice, the power can only be used against those with dual citizenship. The government wants to change the law. This could mean that citizenship can be removed from those with sole British nationality. However, we will have to wait and see precisely what the government announces in its package of measures today.
If a person with sole British nationality is or has been acting in a way that is “not conducive to the public good”, for instance by involving themselves in terrorism, then they can have their passport removed. That can be a temporary measure and does not remove their citizenship.
But Mr Cameron has said he is concerned that Britons who have travelled to fight with Islamic State (IS) in either Iraq or Syria would be prepared to carry out an attack on UK soil upon their return.
The BBC’s political editor Nick Robinson said the home secretary already had executive powers to seize passports in certain cases but these powers could be legally challenged and ministers were worried about appeals taking too long and decisions being overturned.
However, he believed extending powers to remove the citizenship of British nationals was “not a runner”, because it risked breaching UN treaties and could legitimise other countries doing the same in different circumstances.
Instead, he said the UK was looking at working with Germany, Turkey and other countries through which suspected British jihadists travelled to and from the Middle East to alert them to their presence so they could be detained and questioned before setting foot on UK soil.
Agreement has been reached within the coalition on forcing airlines to hand over more information about passengers travelling to and from conflict zones.
Sir Edward Garnier, a Conservative MP and barrister, said there were existing laws to prevent certain people – including potential terrorists and football hooligans – travelling abroad.
However, he said there were legal issues around the prospect of rendering people “even temporarily stateless” and he said the new measures needed to be carefully considered.
“If we make announcements that we cannot follow up on in a practical sense then we make promises we can’t keep,” the former solicitor general told BBC Breakfast.
“What we have to do is balance what is the right thing to do – and there is an expectation the government should be doing more – against what is legally proper to do.”
IS militants have seized swathes of territory in Syria and Iraq and have been condemned for the mass slaughter of religious minorities in the region, including Iraqi Christians and the Yazidi community.
The UK is assisting Iraqi and Kurdish forces fighting Islamic State as well as providing humanitarian aid to those displaced by the fighting.
On Sunday, the RAF delivered 11 tonnes of equipment directly to the northern city of Erbil, including ammunition supplied by other nations and body armour helmets provided by the UK.