Turkish President Recep Tayyip Erdogan has been sworn in as head of state after winning an historic run-off election to extend his two-decade rule for another five years. The 69-year-old leader will later on Saturday name his Cabinet, which will be tasked with handling an economic crisis that has witnessed runaway inflation and the collapse of the lira. "I, as president, swear upon my honor and integrity before the great Turkish nation and history to safeguard the existence and independence of the state," Erdogan said in a ceremony at the parliament in Ankara, broadcast live on television. Erdogan, took the oath of office on Saturday, ushering in his third presidential term that followed three stints as prime minister. President Erdogan was sworn in during a session in parliament before an inauguration ceremony at his sprawling palace complex. Supporters waited outside parliament despite the heavy rain, covering his car with red carnations as he arrived. Erdogan defeated opposition challenger Kemal Kilicdaroglu in a runoff vote held on May 28, after he narrowly failed to secure an outright victory in a first round of voting on May 14. Kilicdaroglu had promised to put Turkey on a more democratic path and improve relations with the West. International observers deemed the elections to be free but not fair. Saturday's inauguration was followed by a lavish ceremony at the presidential palace in the capital attended by dozens of world leaders. Turkey's longest-serving leader faces considerable diplomatic challenges amid tensions with the West. Erdogan won 52.2 percent of the vote while his rival Kilicdaroglu 47.8 percent, official results show. 78 members of the international community attended the oath-taking ceremony. Some of the guests include Venezuelan President Nicolas Maduro, Hungarian Prime Minister Viktor Orban, and Armenian Prime Minister Nikol Pashinyan, according to the state-run Anadolu news agency. Addressing the country's economic troubles will be Erdogan's priority with inflation running at 43.7 percent, partly because of his unorthodox policy of cutting interest rates to stimulate growth. Analysts have warned if current policies continue, the economy is heading for greater turmoil given depleted foreign reserves, an expanding state-backed protected deposits scheme, and unchecked inflation expectations. The lira has undergone a series of crashes in recent years and hit new all-time lows in the days after the vote. Turkey's new members of parliament started being sworn in on Friday in their first session after the May 14 election, also attended by Erdogan. His alliance holds a majority in the 600-seat parliament. Meanwhile, NATO allies are anxiously waiting for Ankara to greenlight Sweden's attempt to join the United States-led defense alliance before a summit in July. Erdogan has been dragging his feet on approving the application, accusing Stockholm of sheltering "terrorists" of the outlawed Kurdistan Workers' Party (PKK), which is listed as a terror group by Ankara and its Western allies. NATO chief Jens Stoltenberg is attending Erdogan's inauguration and will hold talks with him, the alliance said on Friday. Sweden's Foreign Minister Tobias Billstrom said on Twitter "a clear message" emerged at a NATO meeting in Oslo for Turkey and Hungary to start the ratification process. His Turkish counterpart, Mevlut Cavusoglu, responded: "A crystal clear message to our Swedish Friends! Fulfill your commitments arising from Trilateral Memorandum & take concrete steps in the fight against terrorism." Erdogan was sworn in amid a host of domestic challenges ahead, including a battered economy, pressure for the repatriation of millions of Syrian refugees and the need to rebuild after a devastating earthquake in February that killed 50,000 and levelled entire cities in the south of the country. Turkey is also grappling with a cost-of-living crisis fueled by inflation that peaked at a staggering 85% in October before easing to 44% last month. The Turkish currency has lost more than 10% of its value against the dollar since the start of the year. Unconfirmed media reports say Erdogan plans to reappoint Mehmet Simsek, a respected former finance minister and deputy prime minister, to the helm of the economy. The move would signify a return by the country — which is the world's 19th largest economy according to the World Bank — to more orthodox economic policies. — Agencies