Robots could fill the jobs of 3.5 million people in Japan by 2025, a thinktank says, helping to avert worker shortages as the country's population shrinks.

Japan faces a 16 percent slide in the size of its workforce by 2030 while the number of elderly will mushroom, the government estimates, raising worries about who will do the work in a country unused to, and unwilling to contemplate large-scale immigration.

The thinktank, the Machine Industry Memorial Foundation, says robots could help fill the gaps, ranging from microsized capsules that detect lesions to high-tech vacuum cleaners.

Rather than each robot replacing one person, the foundation said in a report that robots could make time for people to focus on more important things.

Japan could save 2.1 trillion yen (10.4 billion pounds) of elderly insurance payments in 2025 by using robots that monitor the health of older people, so they don't have to rely on human nursing care, the foundation said in its report.

Caregivers would save more than an hour a day if robots helped look after children, older people and did some housework, it added. Robotic duties could include reading books out loud or helping bathe the elderly.

"Seniors are pushing back their retirement until they are 65 years old, day care centres are being built so that more women can work during the day, and there is a move to increase the quota of foreign labourers. But none of these can beat the shrinking workforce," said Takao Kobayashi, who worked on the study.

"Robots are important because they could help in some ways to alleviate such shortage of the labour force."

The current fertility rate is 1.3 babies per woman, far below the level needed to maintain the population, while the government estimates that 40 percent of the population will be over 65 by 2055, raising concerns about who will look after the greying population.

Kobayashi said changes were still needed for robots to make a big impact on the workforce.

"There's the expensive price tag, the functions of the robots still need to improve, and then there are the mindsets of people," he said.

"People need to have the will to use the robots."

日本一智囊机构指出，到2025年，机器人将填补日本350万个劳动力空缺，这将有利于缓解该国因人口减少而造成的劳动力不足问题。

据日本政府估计，随着老龄人口的迅速增加，到2030年，日本的劳动力将减少16%。对于一个不习惯也不愿意大规模引入外来劳动力的国家来说，这种状况让人担忧谁能来填补这个劳动力空缺。

智囊机构“机器工业纪念基金会”说，机器人可以来帮忙——小到可探测损伤的微型胶囊，大至高科技真空吸尘器。

该机构在一份报告中称，让机器人参与人类劳动并不是用一个机器人代替一个人，而是让机器人为人们腾出时间去做更重要的事。

该机构在报告中说，如用机器人代替护理人员来看护老人，那么到2025年可为日本政府节约2.1万亿日元（104亿英镑）的养老保险费用。

如果让机器人帮助照顾老人小孩以及做一些简单家务，那么每天可为人节省一个多小时的时间。机器人还能为人们朗读书本和帮助老人洗澡。

研究人员高尾小林说：“老年人的退休年龄推迟到了65岁，日托中心正在建立，尽管这让女性可以出去工作，而且政府也开始实行增加外来劳动力的举措，但这些都无法从根本上解决劳动力不断减少的问题。”

“机器人的重要性就在于，它们在某种程度上可以帮助缓解劳动力短缺的问题。”

日本目前的生育率为平均每个妇女生育1.3个孩子，远远不足以维持人口增长。此外，据政府估计，到2055年，日本40%的人口将超过65岁，这种状况让人担忧谁来照顾这些老龄人口。

小林说，如果要让机器人发挥更大的作用，还需对它们进行改造。

他说：“机器人价格昂贵，功能仍需改善，同时还有人们的观念，必须要让人们愿意使用机器人。”