A top North Korean diplomat has warned that his country is ready to send "more gift packages" to the United States as world powers struggled for a response to Pyongyang's latest nuclear weapons test.

Han Tae Song, ambassador to the United Nations in Geneva, confirmed that North Korea, officially known as the Democratic People's Republic of Korea (DPRK), had successfully conducted its sixth and largest nuclear bomb test on Sunday.

"The recent self-defence measures by my country, DPRK, are a gift package addressed to none other than the US," Mr Han told a disarmament conference.

"The US will receive more 'gift packages' from my country as long as it relies on reckless provocations and futile attempts to put pressure on the DPRK," he added without elaborating.

US Ambassador to the United Nations Nikki Haley yesterday accused North Korean leader Kim Jong Un of "begging for war" with a series of nuclear bomb and missile tests.

She urged the 15-member Security Council to impose the "strongest possible" sanctions to deter him and shut down his trading partners.

But Russia’s UN Ambassador Vassily Nebenzia said today that a US bid for the Security Council to vote on 11 September on new sanctions is a little premature.

Russia is a permanent member of the Security Council and has veto power.

Russian President Vladimir Putin earlier described more sanctions as a "road to nowhere".

Sanctions have done little to stop North Korea boosting its nuclear and missile capacity as it faces off with US.

US President Donald Trump who has vowed to stop Pyongyang from being able to hit the mainland United States with a nuclear weapon.

Ms Haley acknowledged today that more sanctions on North Korea are unlikely to change its behaviour but would cut off funding for its ballistic missile and nuclear programmes.

"Do we think more sanctions are going to work on North Korea? Not necessarily," she told the American Enterprise Institute think-tank in Washington.

"But what does it do? It cuts off the revenue that allows them to build ballistic missiles."

Diplomats have said the Security Council could consider banning North Korean textile exports, banishing its national airline and stopping supplies of oil to the government and military.

Other measures could include preventing North Koreans from working abroad and adding top officials to a blacklist aiming at imposing asset freezes and travel bans.

China accounted for 92% of North Korea's trade in 2016, according to South Korea’s government.

China's foreign ministry said it would take part in Security Council discussions in "a responsible and constructive manner".

German Chancellor Angela Merkel and Japanese Prime Minister Shinzo Abe spoke by telephone today and agreed that sanctions against Pyongyang should be stepped up.

South Korea has said an agreement with its ally the United States to scrap a weight limit on its warheads would help it respond to North Korea's nuclear and missile threat.

South Korea's Asia Business Daily, citing an unidentified source, reported that North Korea had been observed moving a rocket that appeared to be an intercontinental ballistic missile (ICBM) towards its west coast.

The rocket started moving yesterday and was spotted moving only at night to avoid surveillance, the newspaper said.

South Korea's defence ministry, which warned that North Korea was ready to launch an ICBM at any time, said it was notable to confirm the report.

Analysts and South Korean policymakers believe North Korea may test another weapon on or around 9 September, when it celebrates its founding day.

North Korea says it needs to develop its weapons to defend itself against what it sees as US aggression.

South Korea, after weeks of rising tension, is talking to the US about deploying aircraft carriers and strategic bombers to the Korean peninsula, and has been ramping up its own defences.