China must step up and exercise its influence with North Korea in order to resolve escalating tensions in south-east Asia, Theresa May has said.

As she arrived in Hamburg for the G20 summit, the Prime Minister condemned North Korea’s recent successful testing of a new long-range missile and said that she would support a tightening of sanctions against the authoritarian regime.

Speaking to reporters aboard her RAF Voyager plane as it touched down on the tarmac in Germany, the Prime Minister argued that it was “important that we see China playing its role”.

China has historically backed the maverick North Korean regime because of its shared ideological heritage and geographic proximity, but has begun to change its tone in recent years.

Earlier this year China condemned another North Korean missile test but it reacted angrily at the end of June after the US imposed sanctions against a Chinese bank accused of having links to Pyongyang.

“What I think needs to happen is first of all, we absolutely condemn the action that North Korea has taken,” Ms May told reporters.

“What we need to see is a China who can exercise influence on North Korea [and] playing a greater role in doing that. If there are proposals to tighten sanctions and extend sanctions, we will do that.

“On North Korea, it’s important that we see China playing its role and any other [country] who can exercise influence."

In pictures: North Korea military drill Show all 8 1 /8 In pictures: North Korea military drill In pictures: North Korea military drill North Korea's leader Kim Jong Un watches a military drill marking the 85th anniversary of the establishment of the Korean People's Army (KPA) KCNA/Handout via REUTERS In pictures: North Korea military drill A military drill marking the 85th anniversary of the establishment of the Korean People's Army (KPA) is seen in this handout photo by North Korea's Korean Central News Agency (KCNA) KCNA/Handout via REUTERS In pictures: North Korea military drill A military drill marking the 85th anniversary of the establishment of the Korean People's Army (KPA) is seen in this handout photo by North Korea's Korean Central News Agency (KCNA) KCNA/Handout via REUTERS In pictures: North Korea military drill A military drill marking the 85th anniversary of the establishment of the Korean People's Army (KPA) KCNA/Handout via REUTERS In pictures: North Korea military drill A military drill marking the 85th anniversary of the establishment of the Korean People's Army (KPA) KCNA/Handout via REUTERS In pictures: North Korea military drill This image made from video of still images broadcast in a news bulletin by North Korea's KRT, shows what was said to be a 'Combined Fire Demonstration' held to celebrate the 85th anniversary of the North Korean army, in Wonsan, North Korea. KRT via AP Video In pictures: North Korea military drill This image made from video of still images broadcast in a news bulletin by North Korea's KRT, shows what was said to be a 'Combined Fire Demonstration' held to celebrate the 85th anniversary of the North Korean army, in Wonsan, North Korea. KRT via AP Video In pictures: North Korea military drill This image made from video of still images broadcast in a news bulletin by North Korea's KRT, shows what was said to be a 'Combined Fire Demonstration' held to celebrate the 85th anniversary of the North Korean army, in Wonsan, North Korea. KRT via AP Video

Ms May's emphasis on China’s role is similar to that of the US. The American ambassador to the United Nations, Nikki Hayley, said following the latest missile launch that "much of the burden of enforcing UN sanctions rests with China” because “90 per cent of trade with North Korea is from China”.

The Prime Minister also spoke about the US President's controversial decision to withdraw from the Paris Agreement on climate change.