Image copyright Reuters Image caption Trump received the backing of the National Rifle Association

Republican Donald Trump has said he would like people on terror watch lists to be prevented from buying guns, in the wake of the Orlando shootings.

The presumptive presidential nominee tweeted that he would meet the National Rifle Association to discuss the issue.

The NRA responded by saying it would meet him but it already opposes terrorists buying guns.

Forty-nine people were killed in a gay nightclub by Omar Mateen, who had been put on a terror watch list by the FBI.

His wife is also being questioned in connection with the atrocity, the worst mass shooting in modern US history.

Up to now, Mr Trump has been a strong supporter of protecting gun rights and his candidacy was endorsed by the NRA, a powerful gun lobby, last month.

But on Wednesday, he tweeted: "I will be meeting with the NRA, who has endorsed me, about not allowing people on the terrorist watch list, or the no fly list, to buy guns."

Mr Trump made a similar point in a television interview last November but had not mentioned it since the recent attacks.

The FBI has two terror "watch lists". The smaller one bans flying to and from the US and there is also a larger one, which Mateen was on.

Mateen was put on that list for 10 months while under investigation following inflammatory comments at work.

But the FBI concluded there was no evidence he was a terror threat.

The 29-year-old, a US national with Afghan parents, bought an assault rifle and a handgun in early June.

Media playback is unsupported on your device Media caption Orlando shooting witness: Nowhere feels safe

An NRA statement said its position had not changed.

"Anyone on a terror watchlist who tries to buy a gun should be thoroughly investigated by the FBI and the sale delayed while the investigation is ongoing."

Analysis - Anthony Zurcher, BBC News, Washington

On Tuesday it seemed the traditional battle lines were forming on gun regulation following the Orlando attacks.

Republicans warned that "the terrorists win" when politicians like Hillary Clinton take away Second Amendment rights. Democrats in Congress were apoplectic as Republican leadership thwarted their legislative proposals.

The New York Times fretted that strong support for gun-ownership protections could be Donald Trump's key to electoral victory.

And then, with one tweet, the presumptive Republican nominee has turned the debate on its head.

Although Mr Trump boasts how the NRA gave him an early endorsement, many on the right are still suspicious of the man who once supported an assault weapons ban.

Now, on the heels of a rough couple of weeks for the New Yorker, conservatives are once again on the verge of panic. Mr Trump has "caved on defending the Second Amendment," tweeted long-time conservative Trump critic Erick Erickson.

Where the debate goes from here is anyone's guess. NRA officials are likely hyperventilating into paper bags. Congressional Republicans, who would have to pass supporting legislation, almost certainly won't budge.

Mr Trump may have just shown his unpredictable independent streak, but it's on one issue that has been non-negotiable for conservatives so far.

Investigators are still unclear about the motive for the attack and on Wednesday the FBI appealed for more information from the public.

Mateen pledged allegiance to so-called Islamic State as he carried out the attack and people who knew him said he displayed an apparent hatred towards gay people.

Media playback is unsupported on your device Media caption Orlando survivor Angel Colon: "I was thinking I'm next, I'm dead"

Image copyright Getty Images Image caption Vigils have been held all over Orlando since the tragedy

The FBI is also investigating reports that Mateen made several visits to the Pulse nightclub and made contact with other men on gay dating apps.

His father said on Wednesday that he blames his son's actions on the influence of "horrible killer group" Islamic State. He also said the club should have had stronger security.

Supporters of tougher gun laws, like President Barack Obama, have said the attack in Orlando strengthens their cause.

Democrats in the Senate started pushing for gun control on Wednesday, mounting a filibuster - prolonged speaking on the floor to extend debate on legislation.

Senator Chris Murphy from Connecticut, where 26 people died in a school shooting in 2013, wants to force Republicans and Democrats to agree on legislation to deny suspected terrorists from buying guns and requiring universal background checks.