Taiwan's plan to cut its armed forces by a fifth has been held up by political wrangling, a lawmaker said Wednesday, delaying by a year a military reduction driven by improved ties with China.

Taiwan's defence ministry launched the ambitious plan in 2011, aiming to slash the number of service personnel in the army, navy and air force to a record low of 215,000, from 275,000.

But lawmaker Lin Yu-fang, who sits on parliament's defence committee, said the cuts would now be completed in 2015, not 2014 as originally envisaged.

The defence ministry "for the first time admits that the target cannot be reached as scheduled", he said in a statement, citing a report to be read by Defence Minister Kao Hua-chu during a committee meeting Thursday.

The hold-up was due to a delay in amending the legislation that sets out the shape of Taiwan's armed forces amid disagreements between MPs, said the lawmaker.

The plan is part of a defence review that will also see compulsory military service scrapped. Presently, all men aged over 20 are required to spend a year in the armed forces.

Taiwan's relatively large army is a legacy of decades of tensions with China, which has regarded the island as part of its territory awaiting reunification since the two sides split at the end of a civil war in 1949.

But ties between Taiwan and China have improved dramatically since Ma Ying-jeou's China-friendly Kuomintang party took office in 2008 on a platform of boosting trade and tourism links.