KUALA LUMPUR, Nov 30 (Reuters) - Malaysia's palm oil planters are preparing to import an army of migrant workers to boost output hammered by the coronavirus pandemic, but the nation's largest producer said workers are only expected to start arriving by the end of March 2022.

Border closures and a ban on the entry of migrant workers since last year have contributed to an acute labour shortage on plantations -- where 78% of workers are from countries such as Indonesia, India and Bangladesh -- while many have left Malaysia.

The government said in September it would prioritise the return of 32,000 workers for the plantation sector to ease the labour crunch that has clipped output in the world's second largest palm oil producer. Malaysia's Human Resources Ministry told Reuters in October workers would start arriving at the end of this year.

FGV Holdings, which is currently operating at 72% workforce strength, told Reuters it expects the first batch of the 7,000 workers it plans to hire to arrive by the end of the first quarter of 2022 due to additional COVID-19 processes.

"Although the numbers are insufficient to the actual number of shortages, the 7,000 workers are crucial, especially for harvesting," it said in an emailed response to Reuters, adding that any positive impact on production would be seen by the second quarter.

The Malaysian Palm Oil Association (MPOA) estimates the plantation worker shortfall is roughly 75,000, nearly half of which are harvesters urgently needed to pluck the heavy, perishable palm fruit bunches from towering trees.

Malaysia faces a potential production loss of 4.5 million tonnes of crude palm oil in 2021 as a result, MPOA chief executive Nageeb Wahab said.

Palm oil constituted nearly 3.6% of the country's gross domestic product in 2020.

Plantation firms and recruitment agencies have started identifying suitable foreign workers and preparing paperwork, but are awaiting for more guidance from the relevant government agencies in order to arrange travel.

FGV said it has prepared government-approved quarantine centres in Malaysia and in workers' home countries in preparation for incoming recruits.

While workers are expected to enter in time for the peak production season commencing around September 2022, analysts said output may not recover immediately.

"We anticipate that even with the arrival of workers it will take a long time for the plantation sector to recover," said Julian McGill, head of South East Asia at LMC International.

"Plantation companies went to great lengths to keep harvesting during the peak crop, but the longer harvesting rounds and lack of maintenance, particularly pruning, will take at least six months to rectify."

The return of workers could help Malaysia's production to recover by 1 million tonnes in 2022, said Thomas Mielke, the head of German-based analyst firm Oil World, in a webinar last month. (Reporting by Mei Mei Chu; Editing by Ana Nicolaci da Costa)