William Hague said Labour have "learnt nothing from their mistakes" as he helped launch a scathing attack on the party ahead of May's election.
"They are committed from the start to more wasteful spending, more borrowing and higher taxes," the Leader of the Commons said.
"It is in their DNA," Hague added.
British jihadists returning to the UK from Syria after becoming disillusioned with the extremists could be used to dissuade others from going to join the conflict, William Hague said.
The Leader of the Commons said authorities would be prepared to assist former-fighters, if satisfied as to their "good intentions".
His comments come amid reports that some Britons who left groups like Islamic State (IS) fear returning home in case they face arrest.
Speaking on BBC1's The Andrew Marr Show Mr Hague said:
Our top priority has to be the protection of the security of the people of this country, and that is why we will take action where we think people could be dangerous. But the Home Office and the police and the health service are also working together on what we can do to assist those people who come back with good intentions, but of course we have to be sure that they do have good intentions. We haven't had a lot of those people coming back yet and saying they want to be of assistance, but if they do well then of course the Government, the police, the National Health Service, will work with those people and help them to recover and to assist others.
No one political party has a "monopoly of wisdom" on the NHS, outgoing MP William Hague told Good Morning Britain.
The leader of the House of Commons said he thought the Conservative party had done "a very good job" on the NHS and insisted "we all care about the National Health Service".
Former Foreign Secretary William Hague will answer questions in the House of Commons in place of the Prime Minister tomorrow, a spokesperson in David Cameron's office confirmed.
British firms probably supplied the chemicals that have been used to make the nerve agent sarin in Syria, according to Foreign Secretary William Hague.
In a written statement to MPs he said that between 1983 and 1986 a review of the records showed a number of companies exported substances but they had legitimate uses for producing plastics and pharmaceuticals and they were not restricted under UK or international law.
He added: "From the information we hold, we judge it likely that these chemical exports by UK companies were subsequently used by Syria in their programmes to produce nerve agents, including sarin.Some of the companies involved no longer exist."
A UK chemical trader may have sourced some of the substances in question rather than producing them in the UK, he wrote.
Hague said Britain was "playing its full part" in the international effort to eliminate Syria's programme and he expected a ship carrying chemicals to be destroyed will arrive from the country next week.
Foreign Secretary William Hague hailed an European Union agreement with Ukraine, Georgia and Moldova as a "great step forward for them and their democracies".
Congratulations to Ukraine, Georgia, Moldova on signing agreements with EU. A great step forward for them and their democracies
Foreign Secretary William Hague tweeted following his meeting with Kurdish Regional Government leaders in northern Iraq:
Foreign Secretary William Hague wrote on Twitter:
I welcome President Poroshenko's ceasefire plan in #Ukraine. Vital Russia gives visible support including stemming flow of arms