TAIPEI, Feb 6 (Reuters) - Taiwan will seek an extension to the date by which an agreement must be signed with the United States for a batch of weapons deliveries given an ongoing standoff in parliament about defence spending, the island's defence ministry said on Friday.

Taiwan President Lai Ching-te last year proposed a $40 billion special defence budget to counter a rising threat from China, which views the island as its own territory, but the opposition-controlled parliament has instead advanced its own, less expensive proposals which only fund some U.S. weapons.

Taiwan's defence ministry has urged the opposition to approve the spending proposal, warning that any delay could postpone much-needed weapons deliveries, as orders from other countries could move ahead in the queue.

The ministry said it had received from the U.S. government draft Letters of Offer and Acceptance (LOA) price proposals valid until March 15 of this year for TOW anti-tank missiles, Lockheed Martin-made LMT.N Javelin anti-armour missiles and M109A7 self-propelled howitzers.

The first instalment must be paid by March 31, but parliament has not sent the government's defence spending proposal to committee for review, it added.

"The Ministry of National Defence will actively seek an extension from the U.S. side for the LOA signing validity period to avoid the entire case being cancelled due to a failure to sign within the deadline," it said.

LOAs are the legal instrument the U.S. government uses to sell weapons abroad.

The ministry said that it has already coordinated with the U.S. on what weapons it wants under the spending plans and confirming key factors such as willingness to sell, production lines, and delivery timelines.

Parliament should complete its review as soon as possible so that the armed forces can "build up capabilities and prepare for combat, deter aggression, and safeguard national security", it added.

Taiwan's main opposition party the Kuomintang $(KMT)$, which sent a delegation to Beijing this week, says it supports defence spending but has a duty to scrutinise the plans and will not sign "blank cheques".

The U.S. says that it supports Taiwan's efforts to boost spending, something the Trump administration has been asking of all U.S. allies.

"As the State Department and AIT have repeatedly stated publicly, and we've made clear to Taiwan counterparts, we welcome Taiwan's announcement of a $40 billion special defence procurement budget," a State Department spokesperson said in a statement to Reuters.

The American Institute in Taiwan $(AIT)$ is the de facto embassy in the absence of formal diplomatic ties.

(Reporting by Ben Blanchard; Additional reporting by Michael Martina in Washington; Editing by Raju Gopalakrishnan)

((ben.blanchard@thomsonreuters.com;))