BEIJING, Dec 12 (Reuters) - China, the world's most populous country, is expecting a mini-baby boom, state media said on Wednesday, warning also of a "social time bomb" as more men are unable to find wives.

With the world's biggest population straining scarce land, water and energy resources, China has enforced rules to restrict family size since the 1970s.

China says its policies have prevented several hundred million births and boosted prosperity, but experts have warned of trouble ahead from an ageing population and widening gender disparity stemming from a traditional preference for boys.

The "one-child" policy was relaxed in 1984, allowing rural couples to have a second child if their first was a girl. Many of those children were now of "marriageable age", the China Daily said.

"A mini-baby boom is expected to start next year as a result of the country's family planning policy," it said, quoting Zhang Weiqing, minister of the National Population and Family Planning Commission.

"He expects the boom to last for more than 10 years and to put great pressure on the government in its efforts to manage population growth."

According to official figures, the average number of children born to each family is currently 1.8, compared to 5.8 in the early 70s.

In what the China Youth Daily on Tuesday called a "social time bomb", the number of young singles, mostly males, continued to rise.

The paper said that in 2005, single people accounted for 65.89 percent of those aged from 15-29, compared with 51.54 percent in 1995.

"It will become more difficult for low-income men to find suitable spouses as they get older," it said. "A large number of unmarried men could also cause social problems such as violent acts against women." (Reporting by Beijing Newsroom, editing by Nick Macfie)

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