TAIPEI, March 14 (Reuters) - Taiwan's air force scrambled again on Monday to warn away 13 Chinese aircraft that entered its air defence zone, Taiwan's defence ministry said, in the latest uptick in tensions across the Taiwan Strait.

Taiwan, which China claims as its own territory, has complained of regular such missions by the Chinese air force over the last two years, though the aircraft do not get close to Taiwan itself.

Taiwan is currently in a heighten state of alert due to fears China could use Russia's invasion of Ukraine to make a similar military move on the island, though Taipei's government has not reported any unusual Chinese movements.

The number of aircraft involved was well off the last large-scale incursion, 39 Chinese aircraft on Jan. 23, and since then, such fly-bys have been sporadic with far fewer aircraft.

The ministry said the latest mission involved seven Chinese J-10 and five J-16 fighters as well as one Y-8 electronic warfare aircraft, which flew over an area to the northeast of the Taiwan-controlled Pratas Islands at the top end of the South China Sea.

Taiwanese fighters were sent up to warn the Chinese aircraft and air defence missiles were deployed to "monitor the activities", the ministry said, using standard wording for how Taiwan describes its response.

The incident happened on the same day Taiwan grounded its fleet of Mirage 2000 fighters after one crashed on a training mission, though its other jets including F-16s remain active. read more

China has never renounced the use of force to bring Taiwan under its control, and the Taiwan Strait remains a potentially dangerous military flashpoint.