SHANGHAI: China's air force on Saturday began joint training exercises with that of Pakistan, China's defence ministry said, as the two nations' militaries strengthen operational ties.

The countries call each other "all-weather friends", with ties underpinned by long-standing wariness of their common neighbour, India, and a desire to hedge against United States influence in Asia.

"China's Air Force hopes to widen the scope of cooperation and dialogue with all countries and regions," the Chinese defence ministry said in a statement on its website, adding that the exercise, called "Shaheen V", would run until April 30.

China has also long urged Pakistan to weed out what it says are militants from Xinjiang, who may be holed up in the tribal areas on the Pakistan-Afghan border, a region home to a mix of militant groups.

Read: Pakistan Air Force needs to replace 190 planes by 2020

For its part Pakistan wants to upgrade its air force, now dependent on a mostly outmoded fleet of US, French and Chinese fighter jets that Pakistani officials fear can do little against Indian craft or help target domestic insurgents.

In an interview with Reuters on Thursday, Pakistan Air Force second-in-command Muhammad Ashfaque Arain said the bulk of the burden was now borne by a fleet of US made F-16 aircraft.

He saw the purchase of more F-16s as economically unfeasible, however. Instead, Islamabad plans to invest in a joint fighter built with China, the JF-17.

Also read: China's Xinjiang seals Pakistan ties with $2bn in deals