Almost 30 percent of fish stocks monitored by the UN's food agency are overexploited, undermining the crucial role sustainable fisheries play in providing food and jobs for millions, a report said Monday.

"Many of the marine fish stocks monitored by FAO remain under great pressure," the Rome-based Food and Agriculture Organisation (FAO) said in a statement accompanying its 2012 report on world fisheries.

"Almost 30 percent of these fish stocks are overexploited," said the agency, which is urging governments to make every effort to support sustainable fisheries around the world and rebuild overexploited stocks.

"Overexploitation not only causes negative ecological consequences, but it also reduces fish production, which leads to negative social and economic consequences," the report said.

The sector produced a record 128 million tonnes of fish for human food in 2012 through fisheries which provide a source of income for 55 million people.

"Fisheries and aquaculture play a vital role in the global, national and rural economy," said FAO head Jose Graziano da Silva. "The livelihoods of 12 percent of the world's population depend directly or indirectly on them."

But the sector faces an array of problems, including poor governance, weak fisheries management regimes, conflicts over the use of natural resources and the persistent use of poor fishery and aquaculture practices, the report said.

"It is further undermined by a failure to incorporate priorities and rights of small-scale fishing communities and the injustices relating to gender discrimination and child labour," said Arni Mathiesen, FAO's Fisheries head.