The White House has said that US President Donald Trump is supporting efforts to improve federal background checks for gun purchases, days after a shooting at a Florida school killed 17 people.

White House spokeswoman Sarah Huckabee Sanders said Mr Trump had spoken to Republican Senator John Cornyn on Friday about a bi-partisan bill that he and Democratic Senator Chris Murphy introduced, which aims to improve federal compliance with criminal background checks.

"While discussions are ongoing and revisions are being considered, the president is supportive of efforts to improve the federal background check system," Ms Sanders said in a statement.

Mr Trump, who visited survivors of the shooting last Friday, is a strong supporter of gun rights and won the endorsement of the National Rifle Association for his 2016 presidential campaign.

Many Republicans generally oppose measures to tighten gun restrictions, citing the US Constitution's Second Amendment protection of the right to bear arms.

Mr Cornyn and Mr Murphy introduced the bill to improve federal background checks last November, days after a gunman killed more than two dozen people in a church in Texas.

The bill, called the Fix NICS Act, would ensure that states and federal agencies comply with existing law on reporting criminal history records to the national background check system.

Mr Cornyn had complained when introducing the legislation that compliance by agencies was lousy.

Students from the Florida high school where a former student is accused of murdering 17 people last week using an assault-style rifle are planning a "March For Our Lives" in Washington on 24 March to call attention to school safety and ask politicians to enact gun control.