Donald Trump has defended proposals to arm some teachers in schools and signalled he will push to raise the minimum age for buying rifles to 21, amid calls for action to prevent shootings.

The President said the White House was looking at letting “gun adept teachers with military or special training experience” carry a concealed weapon so they could ”immediately fire back if a savage sicko came to a school with bad intentions”.

He suggested arming around a fifth of school staff, which he said would also act as a deterrent to possible shooters.

“I will be strongly pushing Comprehensive Background Checks with an emphasis on Mental Health,” Mr Trump added on Twitter. ”Raise age to 21 and end sale of Bump Stocks! Congress is in a mood to finally do something on this issue – I hope!”

His comments came amid calls for action following the Florida school shooting, in which 17 people were killed by a teenager with a semi-automatic weapon.

The President met survivors of the 14 February massacre at the White House, telling them he would look “very strongly” at calls for educators to be armed.

“If you had a teacher that was adept at firearms they could very well end the attack quickly,” he said.

Mr Trump later hit out at reports of his comments in the media and clarified his stance on the issue.

He tweeted: “I never said ‘give teachers guns’ like was stated on Fake News CNN and NBC. What I said was to look at the possibility of giving ‘concealed guns to gun adept teachers with military or special training experience – only the best. 20% of teachers, a lot, would now be able to .immediately fire back if a savage sicko came to a school with bad intentions.

“Highly trained teachers would also serve as a deterrent to the cowards that do this. Far more assets at much less cost than guards. A ‘gun free’ school is a magnet for bad people. ATTACKS WOULD END!”

He added: “If a potential ‘sicko shooter’ knows that a school has a large number of very weapons talented teachers (and others) who will be instantly shooting, the sicko will NEVER attack that school. Cowards won’t go there... problem solved. Must be offensive, defense alone won’t work!”

Armed teachers could stop shooters before police arrive at schools, added Mr Trump.

Speaking to pupils and parents in the White House, Mr Trump acknowledged the idea of letting teachers carry arms in the classroom was “controversial”.

Asked for a show of hands, some of those present indicated they would be in support of the measure and others said they were against.

A number of pupils who survived the shooting at Marjory Stoneman Douglas High School have called on Congress to introduce stricter gun controls in a bid to prevent future tragedies.

Mr Trump last year blocked an Obama-era rule that would have prevented an estimated 75,000 people with mental disorders from buying guns. The rule was part of his Democrat predecessor’s push to strengthen the federal background check system following the 2012 Newtown school shooting – the deadliest in US history.

Mr Trump aligned himself to the National Rifle Association (NRA), one of the most powerful gun-rights organisations, while running for president and received the more firearms lobby funding than any previous candidate

Following his election, the Republican told the NRA: “The eight-year assault on your Second Amendment freedoms has come to a crashing end.”

The NRA this week rejected calls for a higher minimum age for purchasing rifles.

Public affairs director Jennifer Baker said: “We need serious proposals to prevent violent criminals and the dangerously mentally ill from acquiring firearms.