China activated two aviation routes yesterday that run close to Taiwan's outlying islands of Kinmen and Matsu, officials said, with Taipei condemning the "unilateral measures" as a threat to flight safety.

China's civil aviation authority announced in January it was introducing changes to flights headed south along the M503 route through the Taiwan Strait, which it said would improve efficiency in a congested area.

The move drew condemnation from self-ruled Taiwan, which China claims as part of its territory, with the defence ministry saying the new routes could lead to "an escalation in tensions".

China's aviation authority said two connecting lines on route M503, described as W122 and W123, "will be activated from west to east".