North Korean leader Kim Jong-un has not been seen in public for the past two weeks sparking widespread speculation amid escalating tensions in the Korean Peninsula.

Unconfirmed reports which suggested a coup against the leader have been rubbished by experts in Seoul citing no unusual military movement in the country.

Alongside a flurry of threats from North Korea, Kim's absence has set rumour mills rolling. One question being asked is whether Pyongyang has been forced to tone down its war rhetoric against the US and South Korea.

Kim was last seen in public on 1 April when he headed a parliamentary session. The leader has been missing in action for the last 15 days at a time when the country is set to mark the birth anniversary of his grandfather and former leader of North Korea Kim Il-sung.

It is widely speculated that North Korea will launch a ballistic missile to mark the occasion.

A source familiar with matter told the Seoul-based Yonhap news agency that Kim's absence is a "psychological warfare that could grab attention from South Korea and the United States".

Experts also believe that Pyongyang will not scale down its provocative posture against the US.

Meanwhile, North Korea's staunch ally China has pledged to work together with the US in a bid to restrain Pyongyang.

US Secretary of State John Kerry, who was in Beijing holding talks with top Chinese leaders, said the two largest economies are looking forward to peacefully defusing the tensions.

"To properly address the Korean nuclear issue serves the common interests of all parties. China will work with other relevant parties including the United States to play a constructive role," said Beijing's State Councillor Yang Jiechi.

Neither Washington nor Beijing has spelt out the steps the parties intend taking against North Korea if the situation turns worse.

Kerry, who earlier visited Seoul, is on the last leg of his Asia tour and will shortly visit Japan. Tokyo has also deployed several Patriot missiles to defend its territory in the wake of the North Korean threats.

READ: Kim Jong-un Marks Grandfather's Birthday with Flowers - not Missiles