China will never compromise on sovereignty, President Xi Jinping said Friday ahead of an international tribunal ruling over Beijing's maritime claims, as he celebrated the Communist Party's 95th anniversary.

The ruling party must maintain absolute power in the country, strengthen its military and enhance its role on the world stage, Xi told serried ranks of top officials in Beijing's Great Hall of the People, to rapturous applause.

"No foreign country... should expect us to swallow the bitter pill of harm to our national sovereignty, security or development interests," Xi said, adding: "We are not afraid of trouble."

His remarks come as regional tensions rise over Beijing's claims to nearly all of the South China Sea, with the US sending naval patrols close to artificial islands Beijing has built in the disputed waters.

Xi took an apparent stab at the US, saying: "We will not show up at other people's front doors to flex our muscles. That does not show strength or scare anyone."

An international tribunal in The Hague will rule on July 12 in a case brought by the Philippines challenging China's claims in the strategic waterway.

Beijing insists that the Permanent Court of Arbitration has no jurisdiction over the issue and has boycotted the proceedings.

Since assuming the party's top post in 2012, Xi has rapidly consolidated power while overseeing a more assertive foreign policy and a tighter authoritarian stance at home.

- Chinese wisdom -

In his speech, Xi heaped praise on the ruling party and vowed to maintain the country's centralised Communist-led political system.

"All party comrades must remember what we are constructing is socialism with Chinese characteristics, and not any other ideology," he said.

The Communist party, which had some 88.7 million members at the end of last year, must maintain "absolute leadership," he said.

Xi has won popularity with a much-publicised anti-corruption campaign that has claimed the scalps of several former top-ranked officials.

"The biggest threat to our ruling party is corruption," he said, calling for a "complete purification of the party's political environment".

He credited the Communist party with expelling "imperialism" from Chinese soil, and stressed the country's economic growth in recent decades.

He stressed the need for "Mao Zedong thought" but did not refer to the tens of millions killed in famines and political campaigns launched by the founder of the People's Republic.

The speech contained more than 20 references to "Marxism" and was followed by a rendition of the left-wing anthem "The Internationale" by a brass band.

He also issued a warning to Taiwan's newly elected Beijing-sceptic President Tsai Ying-wen -- saying: "we will resolutely oppose all Taiwanese separatist forces".

Shortly before the ceremony began, a Taiwanese warship mistakenly launched a supersonic "aircraft carrier killer" missile towards the mainland, which landed in the Taiwan Strait, Taipei's navy said.

Xi vowed to "build, in line with our global status and in accordance with national interests, a strong army and consolidate national defence".

He also said that China would take an active role in what he called "global governance", suggesting it was seeking a weightier role in international affairs.

Xi added: "China will actively participate in building a global governance system, and will contribute Chinese wisdom to perfecting such a system".