Candidates for the Democratic race for the White House have clashed on gun control and healthcare in a live TV debate.

While Hillary Clinton leads nationwide, she is facing a threat from Vermont senator Bernie Sanders in key states.

Before the debate in South Carolina, Sanders unveiled a healthcare plan for all American citizens.

Clinton said the move risked derailing healthcare legislation introduced under President Obama.

This was the final Democratic debate before caucuses in Iowa on 1 February.

Former Maryland Governor Martin O'Malley, who is trailing Clinton and Sanders in polls, also took part.

Sanders' universal healthcare plan, announced two hours before the debate started, would see citizens pay what he called "a 2.2% income-based premium" towards healthcare. Companies would pay an extra 6.2% of an employee's income towards the plan.

The plan, Sanders' campaign website said, was a way to "stop forcing working Americans to choose between bargaining for higher wages or better health insurance".

Clinton said any moves to scrap the current Affordable Healthcare Act risked plunging the Democrats into "contentious debate". Instead, the party should work on improving the programme, known as Obamacare.

Sanders responded: "Nobody is tearing this up." He said he wanted to build on Obamacare.

Gun control was the first subject in the debate, that was held near a church in Charleston where nine parishioners were shot dead in June 2015.

Clinton released an advertisement this week attacking Sanders for his attitude towards gun control. His home state, Vermont, has one of the highest rates of gun ownership in the US, with close to one in two households owning a weapon.

In the debate, she again highlighted legislation she said showed that Mr Sanders supported the gun lobby.

But Sanders told the debate he had a "D minus voting record" from the National Rifle Association, and fully supported moves by President Obama for tougher background checks on gun buyers.

O'Malley pointed out restrictions he passed against combat assault weapons in Maryland, adding: "I have never met a self-respecting deer hunter who needed an AR-15 [semi-automatic rifle] to down a deer."

Polls indicate Clinton and Sanders are neck-and-neck ahead of the caucus in Iowa, where voters will decide who they want as their preferred candidate. She had once commanded a large lead.

In New Hampshire, Sanders holds a lead in polls ahead of voting in the primary there eight days later.

(BBC)