HUA HIN, Thailand (Reuters/AFP) - A Southeast Asian summit got off to a troubled start on Friday as hosts Thailand faced off against two neighbours in trade and diplomatic spats, and a new regional human rights body drew withering criticism. Determined to avoid a rerun of embarrassing mishaps at past summits, Thailand deployed a security force of 18,000 backed by naval gunships to the seaside resort town of Hua Hin as leaders gathered. Tensions rose to the surface within hours. In a slap in the face to Thailands rulers, Cambodias Prime Minister Hun Sen offered fugitive former Thai premier Thaksin Shinawatra a job as economic adviser. Thaksin, ousted in a 2006 coup, heavily influences a red-shirted, anti-government protest movement from self-imposed exile in Dubai. Thailand is seeking to extradite him to serve a jail term for corruption. Thaksin can stay in Cambodia as the guest of Cambodia and also be my guest as my adviser on our economy, said Hun Sen, who described the former telecommunications tycoon on Wednesday as an eternal friend who had a residence in Cambodia waiting for him. He likened Thaksin to pro-democracy figure and Nobel Peace Prize winner Aung San Suu Kyi, who has spent 14 of the past 20 years under house arrest or in jail in military-ruled Myanmar. Thai Prime Minister Abhisit Vejjajiva had tough words for Hun Sen, calling him seriously misinformed as the row threatened to overtake other issues at the summit of leaders from the 10-member Association of South East Nations (ASEAN). A trade dispute with the Philippines also deepened. Last week Thailand, the worlds biggest rice exporter, threatened to delay an ASEAN free trade pact unless it could get a fair deal on tariffs from the Philippines, the worlds biggest buyer of the food staple. Those differences could derail an ASEAN Trade in Goods Agreement expected to be signed this weekend, undermining a key plank of an ambitious bid by Southeast Asia and its 540 million people to build an EU-style economic community by 2015. Its a very sensitive issue, were friends, we need to talk this through, Thailands deputy commerce minister Alongkorn Polabutr told Reuters. Southeast Asian leaders also launched a widely criticised new human rights body on Friday at a regional summit where they will also grapple with plans for economic and political integration. The establishment of the commission is yet another significant milestone in the evolution of ASEAN, Abhisit said after leaders of the 10-member bloc inaugurated the ASEAN Intergovernmental Commission on Human Rights. But the launch was marred by a row over the barring of civil rights activists from Myanmar, Cambodia, Laos, the Philippines and Singapore who were meant to meet ASEAN leaders at Hua Hin to discuss the new watchdog. This is an outrageous development, said Debbie Stothard of the independent ASEAN Peoples Forum, which nominated the activists. It is a rejection of civil society and of the democratic process by which they were selected. Non-governmental rights organisations and London-based Amnesty International have expressed concerns over the body, while the UN High Commissioner for Human Rights says it has no clear mandate for victims of abuse. Meanwhile, Southeast Asian countries were embroiled in a new rights row Friday after excluding five activists from rare face-to-face talks with national leaders at a summit in Thailand. The national leaders had been due to meet 10 so-called civil society representatives one from each ASEAN member on Friday morning. But the governments of Cambodia, Laos, Myanmar, the Philippines and Singapore rejected activists from their countries at the last minute, said Debbie Stothard from the ASEAN Peoples Forum, which nominated the activists. Five other activists, from Brunei, Indonesia, Malaysia, Thailand and Vietnam, were told they could go to Fridays meeting but would not be allowed to speak, she said.