Image copyright AFP Image caption Hong Kong's pro-democracy protests have lasted for more than three weeks

Hong Kong leader CY Leung has accused "external forces" of involvement in the territory's pro-democracy protests - claims strongly denied by protesters.

In a TV interview, Mr Leung said the rallies, which have paralysed parts of the territory for three weeks, were "out of control" even for organisers.

The protesters are calling for fully democratic elections in Hong Kong.

They are angered by the Chinese government's decision to vet candidates for the leadership polls in 2017.

Police and protesters have scuffled amid tense stand-offs in recent days.

Student leaders and Hong Kong officials have agreed to hold negotiations on Tuesday. The talks will be broadcast live on television.

'Really irresponsible'

Speaking on a local channel, Mr Leung said the protests were "not entirely a domestic movement, as external forces are involved" - although he declined to give details or name the countries he thought were involved.

Alex Chow, from the Hong Kong Federation of Students, one of the groups leading the protests, said: "To make a statement that there are foreign powers infiltrating this movement right before the discussions, is evidence that CY [Leung] is hoping to crack down on the entire movement.

"As the chief executive of Hong Kong, he should probably have solid evidence before making such a statement. He can't just say there is foreign infiltration and this is really irresponsible."

Image copyright EPA Image caption Although overall protest numbers have decreased, large numbers still remain on the streets

One protester, Jeffrey Hui, told the BBC: "This is something which is purely by citizens, purely by those who live in Hong Kong, those who care about Hong Kong, who stand up and go against the regime."

Mainland Chinese officials have frequently warned against "foreign interference" in Hong Kong, while Chinese state media have accused the West of "instigating" the protests.

Analysts have argued that China could be making allegations of interference to discourage foreign governments from supporting the protests.

Tens of thousands took part in demonstrations earlier this month, demanding full democracy.

Media playback is unsupported on your device Media caption As Celia Hatton reports, some of the protesters see Mong Kok as a key bargaining tool

While protest numbers have dwindled in recent days, activists remain entrenched in the Admiralty area of Hong Kong Island, and in Mong Kok, a residential and shopping district across the harbour.

Mr Leung would not confirm whether the government would attempt to clear the demonstrations again, but said: "We need time to talk to the people, particularly young students. What I want is to see a peaceful and a meaningful end to this problem."

Mr Leung added that the protests had "gone out of control even for the people who started it. They cannot end the movement, which is a major concern".

Image copyright AFP Image caption Clashes have erupted between protesters and police officers

Image copyright EPA Image caption Four graduates hold yellow umbrellas that have come to symbolise the protest movement

Image copyright Reuters Image caption Many protesters have prepared themselves for possible clashes with riot police

Benny Tai, one of the founders of the Occupy Central protest movement, has previously said: "When a social movement provides a citywide political awakening, it can no longer be controlled by the organisers."

"People in power have the ability to fulfil democratic demands, and they are the people who can control the movement."

The protesters, who are mostly students, accuse Mr Leung of failing to stand up to the Chinese Communist Party.

On Saturday night, there were brief clashes as police charged at protesters in Mong Kok.

It was unclear what sparked the charge, with some reports saying protesters had tried to breach barricades.

At least 20 people were reported injured in the scuffles.