BEIJING - Hu Jintao said Thursday that the theory of Scientific Outlook on Development is the most important achievement of the Communist Party of China (CPC) in the past decade and it has become a theoretical guidance for the Party.

"Together with Marxism-Leninism, Mao Zedong Thought, Deng Xiaoping Theory and the important thought of Three Represents, the Scientific Outlook on Development is the theoretical guidance the Party must adhere to for a long time," Hu told about 2,300 delegates at the opening of the Party's 18th National Congress.

The CPC has always been keen to come up with theoretical innovations to guide Party members in resolving practical key problems during the country's reform and opening up.

The Scientific Outlook on Development was proposed by the 16th CPC Central Committee in 2003, against the backdrop of rapid economic growth and a series of problems including excessive consumption of resources, serious environmental pollution and a widening gap between the rich and poor.

The concept has championed people's interests and advocated comprehensive, coordinated and sustainable development. At the Party's 17th National Congress, the concept was written into the CPC Constitution.

Over the past ten years, China has advanced to the world's second-largest economy from the sixth place in the world. Its economic, scientific and technological strength has increased considerably. Its overall national strength and international competitiveness and influence have also been enhanced substantially.

Hu said these historic successes are attributable to the correct guidance of the Party's basic theory, line, program and experience.

The Scientific Outlook on Development was created by integrating Marxism with the reality of contemporary China and with the underlying features of our times, and it fully embodies the Marxist worldview on and methodology for development, he said.

"This theory provides new scientific answers to the major questions of what kind of development China should achieve in a new environment and how the country should achieve it," Hu said.

The Scientific Outlook on Development is the crystallization of the collective wisdom of the Communist Party of China and a "powerful theoretical weapon" for guiding all the work of the Party and country, Hu said.

He noted there is still "much room for improvement in our work" and there are "a lot of difficulties and problems on our road ahead", saying  the unbalanced, uncoordinated and unsustainable development "remains a big problem."

"As we advance toward the future, thoroughly applying the Scientific Outlook on Development is of major immediate significance and far-reaching historical significance for upholding and developing socialism with Chinese characteristics. We must apply it throughout the course of modernization and to every aspect of Party building," he said.

In applying the Scientific Outlook on Development, the whole Party must more purposefully make promoting economic and social development the top priority, take putting people first as the core requirement, make pursuing comprehensive, balanced and sustainable development the basic requirement and take the holistic approach as the fundamental way.

Hu said the salient features of the Scientific Outlook on Development are freeing up the mind, seeking truth from facts, keeping up with the times and being realistic and pragmatic.

He called on the whole Party to boldly engage in practice and make changes and innovations, respond to the call of the times, follow the aspirations of the people, ensure that the Party is always full of vigor and that China always has the driving force for development to open a bright future for developing socialism with Chinese characteristics through the creative practices of the Party and the people.