People on social media are mocking those who send "thoughts and prayers" to victims and their families in the aftermath of mass shootings, after New Zealand said it will ban all semi-automatic weapons on Thursday.

Six days ago, 50 people were killed in a terror attack on two mosques in Christchurch.

Prime Minister Jacinda Ardern said a ban on all military-style semi-automatic weapons and assault rifles was planned for April 11.

The expression "thoughts and prayers" is widely shared on social media in the aftermath of shootings, but is often criticised by those who favour stronger gun controls.

Sites like Twitter were awash with people pointing out the vastly different responses to mass shootings by the US and New Zealand.

People on social media are mocking those who send "thoughts and prayers" to victims and their families in the aftermath of mass shootings, after New Zealand said it will ban all semi-automatic weapons just six days after a terror attack on two mosques.

Prime Minister Jacinda Ardern announced on Thursday that military-style semi-automatic (MSSA) weapons and assault rifles will be banned on April 11.

On Friday, a gunman opened fire on two mosques in Christchurch with an AR-15 semi-automatic rifle, killing 50 worshippers, including children.

"On 15 March our history changed forever. Now, our laws will too," Ardern told a new conference.

Social media users frequently send their "thoughts and prayers" to victims and their families in the aftermath of mass shootings, but the expression has become a target of ridicule by those in favour of greater gun control.

The US has been criticised for failing to increase gun control in the wake of a record 93 school shooting incidents in 2018.

Many social media users pointed out the contrast in response from New Zealand and US authorities.

Andrew Stroehlein, European Media Director at Human Rights Watch, said: "How are those "thoughts and prayers" working out for you, America?"

Author Mike Tommasiello said: "Wow that's weird that New Zealand didn't go with thoughts and prayers first."

Ex-New Orleans Saints running back Reggie Bush tweeted: "We don't need your thoughts and prayers we need action!"

New York State Senator Brad Holyman said: "Actions speak louder than empty thoughts and prayers."

—Senator Brad Hoylman (@bradhoylman) March 21, 2019

Journalist Georgette Jupe said: "The USA could learn a lot from New Zealand."

After the mass shooting in Thousand Oaks, California, in November 2018, Susan Orfanos, the mother of a shooting victim went viral after she told a reporter: "I don't want prayers. I want gun control."