China's most advanced aircraft carrier, the Fujian, has entered service days after a grand commissioning ceremony overseen by Chinese leader Xi Jinping, state media said.

The Fujian, the country's third warship, is equipped with electromagnetic catapults which will allow planes to be launched at higher speeds.

Its launch marked a significant step forward for Beijing, which now has the world's largest navy in terms of sheer number of ships.

China has been expanding its navy at breakneck speed under Xi, putting pressure on the United States and its allies to keep up.

The Fujian can launch three different types of aircraft with its electromagnetic catapult and flat flight deck, according to state media.

The domestically-built vessel can carry planes with heavier weapons and fuel loads so they can strike enemy targets from a greater distance, making it more powerful than China's first two carriers, the Liaoning and the Shandong - both built by the Russians.

State media hailed the Fujian as a "major milestone" in the development of China's navy.

The US is the only other country in the world to have an aircraft carrier with the same electromagnetic catapult system as Fujian.

The Fujian's commissioning ceremony was held in southern Hainan province on Wednesday, during which Xi toured the ship's deck to hear more details about its performance at sea.

State media claimed Xi had personally made the decision to adopt electromagnetic catapult technology.

The reports also said Xi spoke to sailors who lined up along the flight deck and dock, saluting and shouting in unison: "Follow the party's command, fight to win, and uphold fine conduct!"