Labour leader Jeremy Corbyn has accused the Conservatives of trying to “protect the public on the cheap” in a speech focusing on the London terror attack.
Mr Corbyn, who has previously questioned the wisdom of a shoot-to-kill policy, also backed the police to use “whatever force is necessary” to save lives.
His comments mark the end of a pause in Labour’s campaigning after the attack.
The Tories accused him of “desperate promises and evasive soundbites”.
“This was a hastily-arranged speech designed to help Jeremy Corbyn run from his record on counter-terrorism policy, but it failed,” Security Minister Ben Wallace said, saying the Labour leader had opposed previous counter-terror laws.
- Reality Check: What has happened to police numbers?
- Enough is enough, says PM after attack
- Latest updates on London Bridge attack
Most parties suspended their national campaigns following the attack on Saturday night.
Mr Corbyn restarted Labour’s in a speech in Carlisle, in which he attacked the Conservatives’ record in government and called for action to tackle extremism.
He pledged “whatever action is necessary and effective” to protect people.
“That includes full authority for the police to use whatever force is necessary to protect and save life as they did last night, as they did in Westminster in March,” he said.
“You cannot protect the public on the cheap. The police and security services must get the resources they need, not 20,000 police cuts.
“Theresa May was warned by the Police Federation but she accused them of “crying wolf”.”
- What we know so far
- In pictures: London Bridge incident
The Labour leader accused US President Donald Trump of lacking “grace” and “sense” after he criticised London Mayor Sadiq Khan’s response to the attack.
Mr Corbyn also called for “some difficult conversations” with Saudi Arabia and other Gulf states, saying they have “funded and fuelled extremist ideology”.
He accused the government of “suppressing” a report into the foreign funding of extremist groups.
“We have to get serious about cutting off the funding to these terror networks, including Isis here and in the Middle East,” Mr Corbyn said.
On the election, he said there was “no doubt” that Thursday’s vote must go ahead.
Earlier Mrs May confirmed the general election would take place as planned on 8 June and said full campaigning would resume on Monday.
In a speech outside 10 Downing Street, Mrs May also said the UK’s counter-terrorism strategy would be reviewed, and the UK would work with other countries to prevent the internet being a “safe space” for terrorists.
She also said there was “too much tolerance of extremism in our country” and – while it would involve “some difficult and embarrassing conversations” – that must change.