Michel Martelly takes the oath of President during his inauguration ceremony in Port-au-Prince May 14, 2011. [Photo/Agencies]

PORT-AU-PRINCE - Haiti's new President Michel Martelly on Saturday called on all Haitians to work for national unity and reconciliation, and promised to work tirelessly for the country.

"My dear compatriots, the responsibility that you have trusted upon me is an important obligation. The road to victory has been long and painful and achieved by the courage of the Haitian people," Martelly said.

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He said he "will work tirelessly for national unity," and called on all Haitians to work for national unity and reconciliation of the political differences that for decades have torn this island country apart.

Wearing the bright red presidential ribbon, Martelly addressed the more than 1,200 people attending his inauguration ceremony, which was held in front of the collapsed National Palace, a reminder of the massive earthquake that killed at least 250,000 people and devastated Haiti last year.

Local authorities estimated that about one million people joined jubilant crowds celebrating outside the temporary Haitian parliament building.

"This is a new Haiti," said Martelly, pledging that from now on living conditions will improve for the country's 9.7 million people. The Caribbean nation is the poorest in the Western Hemisphere and over 80 percent of the population live below the UN poverty line.

The new president also called on foreign investors to become partners of Haiti's reconstruction, saying he would make sure that the island from now on will be known as "a country of law" so that investors can do business with confidence.

"Haiti is open for business," he stressed.

The inauguration ceremony was attended by members of parliament and dignitaries from across the world, including former US president Bill Clinton, special UN envoy to Haiti and head of the UN Mission in Haiti Edmond Mulet, and presidents and senior diplomats from across the region.

Martelly, widely known as "Sweet Mickey," defeated former first lady Mirlande Manigat in a landslide victory in the presidential runoff in March, garnering 67.7 percent of the total vote.