China National Petroleum Corp, the country's largest oil and gas producer, has pumped the first crude oil through the China-Myanmar oil pipeline and the oil is expected to arrive in China within three weeks, the energy giant said on Wednesday.

Around 1,150 cubic meters per hour of crude began flowing into the pipeline on Tuesday, CNPC said in a statement.

The pipeline is the latest energy cooperation between the two countries, and helps ensure China's energy diversification, the company said.

The pipeline extends for 771 kilometers in Myanmar and 1,600 kilometers in China, starting in Myanmar's Made Island and ending in Yunnan province.

In April, the first oil tanker, Suezmax, offloaded 140,000 tons of crude at Made Island oil port, the starting point of the pipeline.

Zhang Yong, deputy director of CNPC Southeast Asia Pipeline Co Ltd, said the first crude oil will be delivered to a new refinery in Ruili, a city in Yunnan province, within 20 days.

Zhang Guobao, former director of the National Energy Administration, said the pipeline will further enhance the country's energy security.

The project, together with the China-Russia crude oil pipelines and the China-Kazakhstan oil pipeline, will also ensure oil import diversification, he added.

Li Li, energy research director at ICIS China, said with the new pipeline, China's oil and gas imports will no longer have to pass through the Malacca Straits, a narrow channel that connects the Indian Ocean with the Pacific Ocean.

The security of pipeline transmission is much greater than that of shipments by sea, and the pipeline will ensure a stable energy supply to China, she added.