Oil prices fell on Friday, dragged down by prospects of weaker crude demand from China as data showed the country's economy grew at the slowest rate for nearly three years, analysts said.

New York's main contract, West Texas Intermediate crude for delivery in May, dropped 66 cents to $102.98 a barrel.

Brent North Sea crude for May lost 51 cents to $121.20 per barrel in London midday trade.

"The weak (Chinese) GDP data has caused prices to retreat almost immediately, along with other commodities," Justin Harper, market strategist at IG Markets Singapore, told AFP.

China's National Bureau of Statistics (NBS) said the Chinese economy, the world's second-biggest after the US economy, expanded by 8.1 percent in the first three months of 2012, slower than the 8.9 percent year-on-year growth in the previous quarter.

China is the world's biggest user of energy, and the latest growth data reinforced worries that the nation's appetite for crude could weaken as industrial activity slows.

Crude prices have also fallen compared with a week earlier, as traders also react to renewed worries about the eurozone's debt woes and due to weaker oil demand in the United States.

However oil has won support in recent days on political tensions surrounding major crude exporter Iran.

Persuading the country to scale back its enrichment of uranium, which can be used for peaceful purposes but also for nuclear weapons, was set to be the key aim of world powers in upcoming talks.

The US, China, Russia, Britain, France and Germany may also press Tehran, at the meeting in Istanbul on Saturday, to give the UN nuclear watchdog more access to its facilities and answer accusations of a covert weapons programme.

The Iran tensions have supported oil prices for months, with some analysts estimating they have exacted a premium of $10-15 a barrel.

The Islamic republic has vehemently denied Western assertions that it is building a nuclear bomb and has threatened to shut the strategic Strait of Hormuz, a major passageway for a fifth of the world's oil supply, if it is hit with further sanctions.

"Talks between Iran and the UN Security Council this weekend will be key, with many investors buying ahead of the meeting as a poor outcome of the talks may cause short term rises in oil," said Tom Pering, an analyst at energy consultants Inenco.

But he added: "Oil looks set to fall to around $115 a barrel over the next few weeks as a drop in demand and indications of an economic slowdown in China finally drive prices below $120 a barrel for a sustained period."

"Pointers include the continued building of US stockpiles and an indication that the Chinese economic machine may have started a slowdown."

On Thursday, the International Energy Agency (IEA) maintained its forecast of moderate oil demand growth this year but said that a tighter market trend since 2009 seems to be easing after a first-quarter rise in global stockpiles.

The IEA kept its 2012 forecast for growth in oil demand at 0.8 million barrels per day (mbd) to 89.9 mbd, with consumption falling slightly over the summer as is normal and then picking up again.

Also this week, the Organization of Petroleum Exporting Countries put world demand this year at 88.64 mbd, up 0.86 mbd from 2011 and compared with 88.63 mbd in its previous monthly report.

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