The Shadow Foreign Secretary revealed what the Labour Party would do to crack down on terror if they were elected in the General Election on Wednesday, following the London Bridge terror attack.
Speaking to the BBC, Ms Thornberry urged the Government to release a report which has been compiled over the past year-and-a-half, which covers Saudi funding of mosques in the UK.
She also said that she and Labour leader Jeremy Corbyn back a 'shoot to kill policy' despite some confusion about his views on the issue.
She said: “There are a number of other areas and that can be things as wide as we need to look again when we get engaged in international wars and conflicts.
“About what the effect may be on those countries in terms of leaving ungoverned spaces.
Emily Thornberry said a report on Saudi funding of UK mosques should be published immediately.
“Which can come back on us because those ungoverned spaces can be the areas where ISIS can flourish and you can actually have training camps.
“We will look again at the funding in relation to ISIS and be much more rigorous about that.
“And the funding of some of our mosques and the connection in relation to some very rich Saudi Arabian business people.
“Something that there is currently a report which is being piled since the last 18 months. We understand that Theresa May has seen it, it hasn’t been published, we don’t know what is being actioned on it.”
In a later interview with Sky News, Ms Thornberry confirmed her and the Labour Party support a “shoot to kill” policy against terrorists during an attack.
She added: “When it comes to defending people. If somebody is coming up to you with a gun, it is absolutely within the law and indeed the duty of a police officer to kill that person if it means it will stop a threat to life.
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“What I support is police officers having the powers and it being entirely clear that they, of course, must always make a safe and if that means killing someone in order to stop more people killed, of course, that is the case, and of course that is what Jeremy believes in.”
Ms Thornberry reiterated that the Labour Party would put an extra 10,000 police officers on the streets if they are elected in the June 8 vote.
Seven people were killed in the terror attack before the three suspected attackers were killed by police at London Borough Market.
Police offerers killed the suspected attacked within eight minutes of the initial attack.
During the attack, 48 people were injured, and 21 victims are currently in critical condition being treated in hospital.
Police raided properties in Barking, East Ham and Newham, with a number of arrests made overnight.
General Election campaigning is due to restart on Monday, following a pause on national campaigning on Sunday.