Qatar, the small Gulf state that on Tuesday hosts an Arab summit, has become a key regional player thanks to its support for Arab uprisings and the marginalisation of traditional heavyweights. But the \"chequebook diplomacy\" of this energy-rich state -- a staunch US ally -- and its backing for Islamists who have managed to seize power in some countries rocked by the Arab Spring have triggered criticism. The emir, Sheikh Hamad bin Khalifa al-Thani, is \"obsessed by an ambition to leave his heirs a country that counts on the world map after it was practically unknown only 20 years ago,\" said Olivier Da Lage, author of the recently published French book \"Qatar: the new masters of the game.\" \"Qatar\'s place, disproportionate to its size and population, is explained notably by its considerable financial capabilities... and the extended absence of the historical actors in the Arab world,\" he said in reference to Egypt and, to a lesser extent, Saudi Arabia. Qatar has a population of less than two million people, mostly foreign expatriates lured by work opportunities in the desert state that sits on the world\'s third largest natural gas reserves and 13th proven oil reserves. Paul Salem, the director of the Carnegie Middle East Centre, argued that Qatar is not a unique case in history of a small state becoming a regional power, citing Venice among other examples, in a study published in December. \"But this influence poses a question on the impact of the media and the power of money,\" he said of Qatar\'s Al-Jazeera news channel which has played a pivotal role in the coverage of Arab Spring uprisings. In Tunisia, the ruling Islamist Ennahda party is accused of being funded by Doha with the aim of establishing an Islamic state. \"Doha sees in forming an alliance with the Muslim Brotherhood by using chequebook diplomacy a way to create a regional base with economic and political influence in the Middle East and beyond,\" wrote Egyptian French-language weekly Al-Ahram Hebdo in an editorial on March 20. \"The massive financial support awarded by Qatar to Egypt,\" including $5 billion and a pledge to invest $18 billion more over five years, stirs fears of the \"domination this could give the small emirate in defining and formulating the internal and foreign politics of Egypt,\" it said. Qatar is reaping the fruits of its relations with Islamists whom it has always supported, providing shelter to their leaders when they were wanted opponents of regimes in their home countries. It is now the strongest ally of the new governments in Tunisia and Egypt. In Libya, Doha took a spearhead position in the fight against the regime of the late dictator Moamer Kadhafi, sending arms and men to support the rebels while its warplanes, under NATO leadership, swooped on Kadhafi\'s forces. Encouraged by the fall of Kadhafi, who was killed by rebels, Qatar called for the arming and financing of the rebellion against the government of Syrian President Bashar al-Assad. Through its powerful Al-Jazeera news channel, Qatar has realised that \"it could be a key player in the new region in transition, instead of being the protector of an old order in agony,\" said Salem. However, Qatar\'s diplomatic role remains mainly aimed at \"serving the political and economic interests of Qatar itself,\" said Amel Boubekeur, a researcher at the Brookings Institution in Doha.