MACAO, Dec. 19 -- Macao has made great achievements in economic and social development since its return to the motherland 15 years ago, Chinese President Xi Jinping said here Friday evening.

All these progress and achievements are attributable to the full and correct implementation of the principle of "one country, two systems" and the Basic Law, said Xi, who arrived here Friday morning for celebrations marking the 15th anniversary of Macao's return.

"Today, we see a vibrant, stable and harmonious Macao by the South China Sea with a brand new look," said the president at a welcoming dinner.

He said Macao's success is also credited to the unity and hard work of the government of the Macao Special Administrative Region (SAR), the Macao compatriots, and the strong backing of the central government and people of all ethnic groups in China.

Macao, now the masters of their own lives, can definitely unite as one, make unremitting efforts and do a good job in building their homeland under the principles of "one country, two systems", "Macao people administering Macao" and a high degree of autonomy, he said.

These progress and achievements fully demonstrate the strong vitality of the great concept of "one country, two systems," but Macao still faces difficulties and challenges that must be properly managed, he said.

The practice of "one country, two systems," an undertaking with no precedent, will not be plain sailing, the president said.

"While scoring remarkable progress and achievements, Macao has its own share of problems to handle and faces numerous difficulties and challenges that must be properly managed."

The important issue for Macao at present and for some time in the future is "how it can make greater progress on the basis of its achievements in the last 15 years and maintain long-term prosperity and stability."

For Macao to continue to break waves and sail forward, this issue must be properly addressed, he stressed.

Xi will attend an anniversary celebration gathering and the inauguration of the fourth-term government of the Macao Special Administrative Region on Saturday.