MEXICO CITY, July 16 (Reuters) - President Felipe Calderon urged lawmakers on Monday to beef up Mexico's police intelligence, warning that security forces have no way of predicting further rebel bomb attacks on fuel pipelines.

Extra soldiers and federal police were sent last week to guard Mexico's oil wells and pipelines after the left-wing Popular Revolutionary Army, or EPR, said it bombed fuel ducts earlier this month and threatened more attacks.

"It's truly impossible to know ahead of time when and where it's going to happen," Calderon told reporters during a visit with Spanish Prime Minister Jose Luis Rodriguez Zapatero.

"We need to strengthen the government's abilities to investigate and combat crime," he said, urging legislators to approve a law being discussed in Congress to boost police intelligence resources.

Mexico, the world's No. 9 exporter of crude oil by volume and a key supplier to the United States, has a network of pipelines that stretches for more than 14,000 km (8,700 miles), much of that in remote areas.

The EPR set off a series of bombs at pipelines in central Mexico carrying natural gas, liquefied petroleum gas, crude oil and gasoline. It said it would continue its actions until the release of two fellow activists it believes were jailed or abducted in May.

The blasts hit state oil company Pemex's domestic supplies, and forced some manufacturers to temporarily shut down operations, but crude oil exports were not affected.

The Marxist-inspired EPR emerged in 1996 and was active in the poor southern states of Guerrero, Michoacan, Oaxaca and Chiapas, but has always kept a low profile and mainly conducted its campaign via the Internet in recent years.

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