* Iran says discoveries treble previous uranium estimates
* Sites identified for 16 more nuclear plants
* Announcement timed just before talks resume (Adds quote from nuclear chief, analysis and background)
By Marcus George
DUBAI, Feb 23 (Reuters) - Days before resuming talks over its disputed atomic programme, Iran said on Saturday it had found significant new deposits of raw uranium and identified sites for 16 more nuclear power stations.
State news agency IRNA quoted a report by the Atomic Energy Organisation of Iran (AEOI) which said the reserves were discovered in northern and southern coastal areas and had trebled the amount outlined in previous estimates.
There was no independent confirmation. With few uranium mines of its own, Western experts had previously thought that Iran might be close to exhausting its supply of raw uranium.
"We have discovered new sources of uranium in the country and we will put them to use in the near future," Fereydoun Abbasi-Davani, head of the AEOI, was quoted as saying at Iran's annual nuclear industry conference.
The timing of the announcement suggested Iran, by talking up its reserves and nuclear ambitions, may hope to strengthen its negotiating hand at talks in Kazakhstan on Tuesday with the United States, Russia, China, Britain, France and Germany.
Diplomats say the six powers, known as the P5+1, are set to offer Iran some relief from international sanctions if it agrees to curb its production of higher-grade enriched uranium.
The West says Iran's enrichment of uranium to a fissile purity of 20 percent demonstrates its intent to develop a nuclear weapons capability, an allegation the Islamic republic denies.
FROM MINE TO CENTRIFUGE
The enriched uranium required for use in nuclear reactors or weapons is produced in centrifuges that spin uranium hexafluoride gas (UF6) at high speeds. The UF6 is derived from yellow cake, a concentrate from uranium ore discovered in mines.
Iran's reserves of raw uranium now stood at around 4,400 tonnes, taking into account discoveries over the past 18 months, IRNA quoted the report as saying.
In another sign that Iran is intent on pushing forward with its nuclear ambitions, the report also said 16 sites had been identified for the construction of nuclear power stations.
It did not specify the exact locations but said they included coastal areas of the Gulf, Sea of Oman, Khuzestan province and the Caspian Sea.
Iranian authorities have long announced their desire to build more nuclear power plants for electricity production. Only one currently exists, in the southern city of Bushehr, and that has suffered several shutdowns in recent months.
The announcements could further complicate the search for a breakthrough in Kazakhstan, after three unsuccessful rounds of talks between the two sides in 2012.
"We are meeting all of our obligations under the nuclear Non-Proliferation Treaty and we should be able to benefit from our rights. We don't accept more responsibilities and less rights," Saeed Jalili, Iran's chief nuclear negotiator, was quoted as telling Saturday's conference.
In what Washington has called a provocative move, Iran is also installing new-generation centrifuges, capable of producing enriched uranium much faster, at a site in Natanz in the centre of the country.
Western diplomats say the P5+1 will reiterate demands for the suspension of uranium enrichment to a purity of 20 percent, the closure of Iran's Fordow enrichment plant, increased access for International Atomic Energy Agency inspectors and agreement to address concerns on existing uranium stockpiles.
In return, the latest embargoes on gold and metals trading with Iran would be lifted. Iran has criticised the offer and says its rights need to be fully recognised.
"If the P5+1 group wants to start constructive talks with Tehran it needs to present a valid proposal," said Jalili. "It needs to put its past errors to one side ... to win the trust of the Iranian nation."
In a statement issued before the Iranian announcement, German Foreign Minister Guido Westerwelle said the six-power group wanted to enter a 'substantial negotiation process' over Tehran's nuclear programme.
"The talks in Almaty are a chance which I hope Iran takes," he said. (Additional reporting by Alexandra Hudson in Berlin; Editing by Mark Trevelyan)