Image copyright AP Image caption Democratic Senator Chris Murphy staged a marathon address in the Senate, demanding action on gun control

A US Democratic senator has led a 14-hour filibuster to demand a vote on gun control legislation following the massacre at a gay club in Florida.

Chris Murphy spoke from Wednesday morning into Thursday. The tactic enables senators to block proceedings.

He said he had secured commitments from Republicans to hold a vote but his recommendations are not likely to pass.

Sunday's mass shooting in Orlando was the worst in recent US history, with 49 people dead.

Dozens of people remain in hospital, some in a critical condition.

President Barack Obama and Vice-President Joe Biden are due to visit Orlando later on Thursday.

In another development, it emerged that the gunman, Omar Mateen, made a series of Facebook posts before and during his attack in which he raged against the "filthy ways of the West".

Mateen also said on Facebook: "America and Russia stop bombing the Islamic state."

The Senate Homeland Security Committee has asked Facebook to provide information on Mateen's online activity.

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

Image copyright Reuters Image caption Mourners attended the wake for one gun attack victim, Javier Jorge Reyes, in Orlando

Image copyright Getty Images Image caption Funerals for the victims are due to be held over the next few days.

Senator Murphy began the filibuster at 11:21 on Wednesday, vowing to stay on the Senate floor "until we get some signal... that we can come together".

Much of his speech focused on the mass shooting at Sandy Hook Elementary School in his home state of Connecticut in 2012, where 26 people died.

Senator Murphy said he wanted to force Republicans and Democrats to agree on legislation to deny suspected terrorists the right to buy guns and require universal background checks.

"For those of us that represent Connecticut, the failure of this body to do anything, anything at all in the face of that continued slaughter isn't just painful to us, it's unconscionable," he said.

He later tweeted: "I am proud to announce that after 14+ hours on the floor, we will have a vote on closing the terror gap & universal background checks."

Gun control is a divisive topic in the US, where the right to bear arms is enshrined in the constitution.

Earlier on Wednesday, presumptive Republican presidential nominee Donald Trump said anyone on a terror watch list should be prevented from buying guns.

He tweeted that he would meet powerful lobby group the National Rifle Association to discuss the gun control issue.

Image copyright Getty Images Image caption There has been an outpouring of grief for those killed by Omar Mateen

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

Until now, Mr Trump has been a strong supporter of protecting gun rights and his candidacy was endorsed by the NRA.

Just over half of Americans - 51% - disapproved of his initial response to the shooting, in which he repeated a call to temporarily ban Muslims from entering the US, an NBC poll showed.

The same poll found 57% of US citizens think gun laws should be more strict.

Vice-President Biden, speaking at a gun-control fundraising event in Washington, said the idea that a suspect on a terror watch list could still legally buy guns was absurd.

He said it had taken seven years for Congress to approve a ban on assault weapons which expired in 2004.

"I refuse to give up. We refuse to give up. It took me seven years to get the first ban put in place. There is no reason why we should ever stop," he said.

Mateen was on an FBI terror watch list but investigators concluded there was no evidence he was a threat.