SANTIAGO: A billionaire media magnate, Sebastian Pinera, is to become the next president of Chile after a runoff election that put an end to a 20-year hold on power by the left-wing coalition of outgoing head-of-state Michelle Bachelet.

Bachelet's defeated candidate, Eduardo Frei, a former president himself, conceded defeat after an official count of most ballots showed Pinera had picked up 52 percent to his 48 percent.

Bachelet was constitutionally barred from seeking another term.

The victory by Pinera, 60, marked the defeat of the Concertacion coalition of four left-wing and centrist parties that had governed Chile since the 1990 exit of dictator General August Pinochet.

Chile's very wealthy president-elect Sebastian Pinera

The billionaire, who owns one of Chile's four television networks and a big stake in flagship airline LAN among many other business interests, is seen likely to continue social policies that left Bachelet with skyhigh popularity ratings of around 80 percent.

But, in a victory speech before 30,000 supporters, he promised reforms to "break down the walls dividing us and build new bridges to bring us together."

He told Concertacion's defeated rival Frei that "our country needs unity -- the problems facing us today are big and challenging and require unity."

When he cast his ballot, he said the change he represented would be "like opening the window to let fresh air in."

Pinera easily won the first round of the presidential elections on December 13, but then saw his lead narrow to a statistical dead heat with Frei as Bachelet leveraged her popularity in defense of her candidate.

In the end, he squeaked through, according to an official count from 60 percent of polling stations. Complete results were expected by the early hours of Monday.

Bachelet, who had assured the electorate she would welcome whoever won, telephoned a smiling Pinera to congratulate him.

Frei also wished his rival luck.

"The majority of Chileans gave him their trust to direct the fate of the country for the next four years," he said as he conceded the race.

"I hope that what will prevail will be dialogue, the search for consensus and the retention of social conquests that were hard-won and which have been transformed into a symbol of our relationship with the world," he said.

Some 8.3 million people were eligible to vote in Chile, one of Latin America's most prosperous nations.

Interior Minister Edmundo Perez Yoma confirmed Pinera's victory by saying: "The country today wanted a change. It has swung to the right, and we wish the new government all the best."

Some of the first issues Pinera will have to address, however, are potential conflicts of interest highlighted by Bachelet in the run-up to Sunday's election.

Pinera, who Forbes magazine says has a fortune of 1.2 billion dollars, has investments in many activities in Chile, and the outgoing president suggested strongly that maintaining them could raise serious questions.

He has sought to dodge the tag his critics put upon him that he was the Chilean version of Italian Prime Minister Silvio Berlusconi, notably by setting up a blind trust to handle much of his fortune and promising to divest his 26-percent stake in LAN before taking office March 11.

He said, however, that he would hold on to his football club.