Beijing:  China's biggest political event, the Communist Party congress that determines who rules the country and its direction for the next term, has begun here on Wednesday under tight security.

President Xi Jinping is addressing more than 2,000 delegates in the capital, Xinhua news agency reported.

The closed-door summit that takes place once every five years was expected to finish next week. Xi, who became the leader in 2012, was expected to remain as the party chief, the BBC reported.

Shortly after the congress ends, the party is expected to unveil the new members of China's top decision-making body, the Politburo Standing Committee, who will steer the country.

Xi began his speech listing China's achievements during his term, and said socialism with Chinese characteristics had entered "a new era".

China's socialist democracy is the broadest, most genuine, and most effective democracy to safeguard the fundamental interests of the people, he said at while opening the 19th session of the congress.

He called on party members to "always share our fate with the people, always keep the better life for the people in mind".

Xi said China will not close its door to the world, and it will only become more and more open.

"Openness brings progress, while self-seclusion leaves one behind," Xinhua quoted Xi as saying inside the Great Hall of the People here.

He also spoke about the success of his wide-reaching corruption crackdown within the party that has punished more than a million officials, the BBC said.

Beijing is decked out in welcome banners and festive displays for the congress.

However, there is a high security alert. Long lines were seen earlier this week at railway stations due to additional checks at transport hubs.

The congress has also affected businesses, with some restaurants, gyms, nightclubs and karaoke bars reportedly shutting down due to tightened security rules, and accommodation-booking websites like Airbnb cancelling bookings in central Beijing, the BBC said.