(Adds Kerry comment on South China Sea, climate change)
By Arshad Mohammed and Ben Blanchard
BEIJING, Feb 14 (Reuters) - U.S. Secretary of State John Kerry said on Friday China is willing to exert more pressure to get North Korea to give up its controversial nuclear programme and take additional steps to achieve this goal.
Speaking in Seoul before leaving for Beijing, Kerry said China should be doing more to help nudge Pyongyang - which has rattled the region with nuclear tests and angry rhetoric - into line.
In Beijing, he told reporters that he was pleased that China "could not have more forcefully reiterated its commitment" to the goal of denuclearising North Korea.
"I encouraged the Chinese to use every tool at their disposal, all of the means of persuasion that they have, building on the depths of their long and historic and cultural and common history (with North Korea)," he said.
"But they made it very clear that if the North doesn't comply and come to the table and be serious about talks and stop its programme ... that they are prepared to take additional steps in order to make sure that their policy is implemented," Kerry added.
"Now what we are talking about is sort of the specifics of how you do that. And they put some ideas on the table, and we put some ideas on the table," he said.
Chinese Foreign Minister Wang Yi told Kerry that China would work with all parties concerned, including the United States, to play a constructive role for the region's peace and stability.
"China will never allow chaos or war on the Korean Peninsula," Wang said, according to China's Foreign Ministry. "China is serious on this, as shown not only in our words but in our actions," Wang said.
North Korea was raised during Kerry's meeting with Chinese President Xi Jinping, according to the Foreign Ministry, with Xi "setting forth China's stance". The ministry provided no other details.
The East and South China Seas featured prominently on Kerry's agenda too, with him calling for a "more rule of law based, less confrontational regime".
The United States has been increasingly uneasy about what it sees as China's effort to gain creeping control over waters in the Asia-Pacific region, including its Nov. 23 declaration of an air defence identification zone (ADIZ) in an area of the East China Sea that includes islands at the centre of a dispute with Japan.
China also claims about 90 percent of the 3.5 million square km (1.35 million square miles) South China Sea, depicting what it sees as its area on maps with a so-called nine-dash line, looping far out over the sea from south China.
China and the Association of South East Asian Nations have been discussing a code of conduct for the South China Sea, and Kerry said he believed China was ready and wanted to achieve that goal.
"That would help reduce tensions that stem from the territorial and maritime disputes and, in the meantime, it's very important that everybody build crisis management tools and refrain from coercive or unilateral measures to assert whatever claims any country in the region may have."
Wang said China was committed to a peaceful resolution for both the East and South China Seas disputes, but urged the United States not take sides and said China had an "unshakable resolve" to protect its sovereignty.
The United States should "respect historical facts and China's sovereign interests, adhere to an objective and impartial stance and take tangible actions to promote mutual trust in the region so as to safeguard regional peace and stability", Wang said.
Brunei, Malaysia, the Philippines, Vietnam and Taiwan also have claims over the South China Sea, or at least parts of it.
Kerry said he told China it would be a bad idea to establish an air defence identification zone in the South China Sea, similar to the one it set up over the East China Sea late last year, which prompted protests from Washington, Tokyo and Seoul.
"We have made it very clear that a unilateral, unannounced, unprocessed initiative like that can be very challenging to certain people in the region, and therefore to regional stability," he said.
China suggested this month it did not need such a zone for the South China Sea as it did not feel threatened by countries in Southeast Asia.
Kerry's talks did not just focus on regional diplomacy with climate change on the table too.
"We need to see if working together we could identify any further steps that we may be able to take, specifically with respect to arrival at meaningful targets with respect to the 2015 climate change conference that will take place in Paris in December of next year," Kerry said.
(Additional reporting by Sui-Lee Wee; Writing by Ben Blanchard; Editing by Robert Birsel)