A grand ceremony is held at the Great Hall of the People in Beijing on Friday to mark the 95th anniversary of the founding of the Communist Party of China. LIU WEIBING / XINHUA

President Xi Jinping vowed with a rare serious tone to safeguard sovereignty and territorial security on Friday, ahead of the decision in the arbitration case over China's maritime claims, as the ruling Communist Party of China celebrated its 95th birthday.

"No foreign country ... should expect us to swallow the bitter fruit of damage to our sovereignty, security and development interests," said Xi, who is also head of the CPC. He added that China will neither make trouble nor be afraid of trouble.

The president's remarks came amid rising tension in the South China Sea. The ruling in the arbitration case that the Philippines unilaterally initiated against China over the South China Sea will be announced on July 12.

The decision will be made by the Arbitral Tribunal appointed by the Permanent Court of Arbitration in The Hague. China insists that the court has no jurisdiction over the issue.

China will not resort to the threat of force, Xi told an audience including military officers, model workers and ethnic groups, adding that "flaunting power everywhere will not reflect strength, and it will not scare anyone".

The president also emphasized the political foundation of opposing "Taiwan independence" and sticking to the 1992 Consensus, which states that the mainland and Taiwan are parts of one China.

"We firmly oppose the 'Taiwan independence' secessionist activities," Xi said.

During the 80-minute speech, Xi also said that corruption is the biggest danger to the CPC.

History has selected the CPC to lead China, but if the Party does not manage itself properly and listen to the people, history will discard it, Xi warned.

"We must have a staunch will, not let up on our zero-tolerance attitude, investigate all cases and punish those who are corrupt, to give corrupt elements no place to hide in the Party," he added.

Xi called on the 88 million Party members to "stay true to the mission" taken up by the CPC 95 years ago and to "uphold the fighting spirit" of the Party's founding members, as well as their commitment to the people.

China's anti-graft authorities have taken serious, unprecedented measures to fight corruption since Xi was elected as head of the CPC more than three years ago. A large number of senior officials, including former top security official Zhou Yongkang, have been sentenced since then.

In his speech, Xi said China will actively participate in the building of a global governance system and strive to contribute Chinese wisdom to the improvement of global governance.

"China will work with people of all countries in the world to push the world order and global governance system toward a more just and reasonable direction," he said.

Colin Patrick Mackerras, an Australian scholar who was among the 20 foreign experts invited to attend the ceremony, said that the CPC has made great achievements in the past decades, and the Party is facing more challenges, including corruption.

Li Junru, former vice-president of the Party School of the Central Committee of the CPC, said that he was impressed by Xi's call to "stay true to the mission and keep moving forward".

"The decline of a party always starts with the fading of faith, and to 'stay true to the mission' is to keep faith in mind," Li said.