The government should take tougher action to prevent would-be British jihadis from travelling to Iraq and Syria to fight for Islamic State (Isis) and force those who return to Britain to undergo a process of "de-radicalisation", Ed Miliband has said.

The Labour leader said the government should revisit the decision to scrap the control orders regime for terror suspects, after the terror threat level to the UK was raised from substantial to severe.

His comments come ahead of David Cameron's announcement of new counter-terrorism measures in parliament on Monday. The prime minister and Nick Clegg will spend the weekend discussing measures to tackle the threat posed by UK terror suspects.

Cameron said on Friday that there were "gaps in our armoury" which needed to be filled after counter-terrorism experts warned that an attack on the UK was "highly likely".

Writing in the Independent, Miliband stressed the need for a "multilateral alliance" combining political, diplomatic and humanitarian action to counter the "perverted mission" of Isis in the Middle East.

In the UK, he said, "we should act with clarity and determination" to tackle the threat from extremists.

"Such action must include an overhaul of the Home Office Prevent programme to equip communities with the tools to stop young people being sucked into extremist ideology," he said.

"We should also do more to prevent potential fighters from travelling to the region, and promote an effective, mandatory programme of de-radicalisation for anyone who is drawn into the fringes of extremism in Syria and Iraq."

He highlighted concerns raised by David Anderson, the independent reviewer of counter-terrorism legislation, about terrorism prevention and investigation measures (Tpims).

Anderson has recommended stronger measures to restrict the movements of people subject to Tpims, including powers similar to those under the scrapped control order regime allowing the authorities to relocate a terror suspect to another area.

Miliband said: "For the most serious and high-risk cases, as the independent reviewer on terrorism has recommended, the government should strengthen existing powers, including revisiting the case for control orders."

At a Downing Street press conference Cameron insisted there would be no "kneejerk response" to the events in the Middle East, and insisted people should continue to "go about our daily lives in our normal way".

But as the terrorist threat to the UK was raised from substantial to severe, the prime minister warned that extremism in Iraq and Syria posed a greater danger to Britain than al-Qaida.

Cameron, police and intelligence officials have been concerned for months about the threat to the UK posed by British jihadis returning to Britain after travelling to Syria or Iraq.

During the press conference, he highlighted the danger of extremists returning to Britain and said the "scale of this threat is growing".

"I said very clearly last week that there would be no kneejerk response," he said. "But we have to listen carefully to the security and intelligence officers who do so much every day to keep us safe.

"It is becoming clear that there are some gaps in our armoury, and we need to strengthen them.

"We need to do more to stop people travelling, to stop those who do go from returning, and to deal decisively with those who are already here.

"I will be making a statement in the House of Commons on Monday.

"This will include further steps to stop people travelling, with new legislation that will make it easier to take people's passports away."

The prime minister said the murder of the US journalist James Foley, apparently by a British jihadi, was "clear evidence – not that any more was needed – that this is not some far off [problem], thousands of miles away, that we can ignore".

The threat level was raised from substantial to severe by the Joint Terrorism Analysis Centre (JTAC) due to fears about British jihadis returning from Iraq and Syria.

The change means a terrorist attack is considered "highly likely", although the home secretary, Theresa May, stressed there was no specific intelligence.

"The increase in the threat level is related to developments in Syria and Iraq where terrorist groups are planning attacks against the west," May said. "Some of those plots are likely to involve foreign fighters who have travelled there from the UK and Europe to take part in those conflicts."

Speculation is mounting that the government could bow to pressure for Tpims to be beefed up. There have been calls for powers to impose "internal exile" on suspects, a key part of the old control orders regime, to be restored.

Cameron is to push for more coordinated European action to track jihadis at a summit in Brussels.

The UK wants to revive a directive that would enable police and security services across the EU to share passenger records.

National leaders have signed off the arrangements – but they have stalled in the European parliament after MEPs expressed concern about civil liberties and privacy.