Air China Ltd and Virgin Atlantic Airways have reached a codeshare agreement to expand the coverage of both carriers into and out of China, the companies said in a joint statement yesterday.Beijing-based Air China, the nation's flagship carrier, will codeshare on Virgin Atlantic's daily services between London Heathrow and Shanghai starting on July 1.Virgin Atlantic will put its code on Air China's daily services between Beijing and London Heathrow at the same time, the carriers said.Tickets will go on sale starting on April 15.The codeshare cooperation will help Air China consolidate its networks in Shanghai, where it doesn't have direct links to London, and allow the UK carrier to tap the Beijing-London route, industry officials said.In addition, the airlines worked out a frequent-flyer miles deal that allows clients of either carrier to earn credit when they travel with the codeshare partner."The cooperation with Virgin Atlantic is one of the important steps Air China is taking to fulfill its strong commitment to provide passenger-oriented services," said Cai Jianjiang, the carrier's executive vice president.Meanwhile, Air China's service between Beijing and London Heathrow will be increased from five to seven a week.Virgin Atlantic was the first UK airlines to offer direct flights between London and Shanghai in 1999 and has flown about 400,000 passengers on the route since then.