(Corrects to change position at QIA, paragraph 12)
* Transfer plan disclosed to Arab, Western diplomats
* They say reason appears to be wish for younger rulers
* Retirement of emir would be rarity in Gulf Arab politics
* Qatar world's biggest LNG exporter, diplomatic heavy hitter
By William Maclean and Sami Aboudi
DUBAI, June 24 (Reuters) - Qatar appeared on Monday to be preparing its population for new leadership that could see the emir and prime minister step down, a step analysts say would not herald big changes in energy, investment or foreign policies.
The Gulf Arab state is geographically tiny, with two million people, but also the world's largest exporter of liquefied natural gas, a global investment powerhouse, a growing force in international media and sport, and a financial backer of Arab Spring revolts in alliance with the Muslim Brotherhood.
The Qatari-owned al Jazeera television channel said the emir, Sheikh Hamad bin Khalifa al-Thani, 61, would meet ruling family members and decision-makers on Monday "amid reports that he intends to hand over power to his crown prince, Sheikh Tamim".
The satellite channel said it had learned of the news from "reliable Qatari sources", but provided no further details.
There was no mention on Monday morning of the meeting in Qatari newspapers or the state news agency, but Qatari Twitter users sent a variety of supportive messages to Sheikh Hamad.
Qatar's interior ministry account said somewhat cryptically on its Twitter account, "Spreading rumours that lack credibility will hurt the community. Be supportive of the country," as rumours swirled over a possible speech on the event.
Diplomats said earlier this month the emir was considering an orderly transfer of power that would probably begin with the departure of the powerful prime minister and foreign minister, Sheikh Hamad bin Jassim al-Thani, 53.
Arab and Western diplomats said they understood the motive was the emir's desire to have a smooth transition to a younger generation. Such a transition would be unusual for Gulf Arab states, where leaders usually die in office.
Sheikh Tamim is 33, young compared to other Gulf rulers.
Diplomats said they expected the reshuffle to take one of two courses - either Sheikh Tamim would become prime minister until he takes over as emir, or Deputy Prime Minister Ahmed al-Mahmoud would become the next prime minister.
Qatar is a one-family absolute monarchy that has ruled over the Gulf peninsula for more than 130 years.
Sheikh Hamad Bin Jassim has been prime minister since 2007 and has played a central role in positioning Qatar as power broker in the region. He is also vice-chairman of the board of the Qatar Investment Authority (QIA), a position he is expected to retain. QIA has estimated assets of $100 billion to $200 billion.
Widely seen as a savvy dealmaker, Sheikh Hamad bin Jassim has personally negotiated some of the sovereign wealth fund's most high-profile investments, including talks with Glencore's chief last year when the fund demanded better terms for backing the firm's acquisition of Xstrata. The companies eventually merged to create Glencore Xstrata.
The emir has elevated Qatar's international profile in recent years through the launch and development of the Al Jazeera television network, as well as its successful bid to host the 2022 soccer World Cup tournament.
The Gulf state has played a substantial role in promoting Arab Spring protests, lending significant support to rebels who ousted former Libyan leader Muammar Gaddafi in 2011 and to a continuing uprising against Syrian President Bashar al-Assad.
It has also played host to a delegation of the Afghan Taliban, which opened an office in Doha last week in preparation for expected talks with the United States about how to end a 12-year-old conflict in Afghanistan.
Other political crises and wars Qatar has tackled include Yemen, Somalia, Lebanon, Darfur and the Palestinian territories, often arranging for peace talks on its own soil to try to prove it can punch above its weight in international diplomacy.
Eman Ebed Alkadi of Eurasia Group consultants wrote that she did not expect Qatari domestic priorities or its foreign policies to change significantly with a change of ruler.
"Tamim has controlled key policies in Qatar for some time, and shares his father's views on political development in Qatar and economic diversification," Alkadi wrote.
National budgets had been agreed up until 2016-2017, Alkadi said, and with preparations for the World Cup in full swing, much change in domestic momentum was unlikely.
When he took power at age 44, the emir was among the youngest leaders in the region. Viewed as less aloof than other Gulf Arab monarchs, he could often be found at his favourite café in Doha's souq, talking with the patrons.
Qatar is the world's largest exporter of LNG, an achievement that set the country on a track to achieve double-digit economic growth for several consecutive years, during a time when many Western nations were mired in recession.
This spurred a population boom, with inhabitants surging from 500,000 to 1.9 million in the last decade.
Revenue from gas exports helped fund a string of high-profile purchases by the sovereign wealth fund, including the acquisition of London department store Harrods as well as stakes in oil majors Total and Shell.
But in 2005 Qatar declared a moratorium on development of the North Field to allow the impact of a rapid increase in output on the reservoir to be studied. The moratorium is expected to last until 2015 and likely beyond.
Twitter hashtag #thank you Hamad in Arabic was growing in popularity on the social media website on Monday. One user said: "Today is a new step in the history of the state of Qatar." (Additional reporting by Ahmed Tolba, Amena Bakr and Yara Bayoumy; Writing by Sami Aboudi; Editing by William Maclean and Mark Heinrich)