The BBC's Richard Collings: 'It's a framework for some austere times ahead'

In a speech immediately after his victory, he said: "I receive the country with its finances in a disastrous state. One of the most urgent priorities of my government, therefore, will be to restore confidence among economic agents and put the budget house in order.

"We're going to propose to the country, Congress and the international financial community a serious and vigorous fiscal adjustment programme which we will carry out promptly."

Troubled economy

Over the past few weeks Colombia's currency, the peso, has been hit by a wave of speculative attacks.

Its sharp fall in value against the US dollar has led to massive Central Bank intervention. Local stock markets have also fallen to 17 month lows.

Mr Pastrana said his other priority would be to carry out his election pledge to hold talks with left-wing guerrillas groups. Meetings could take place with rebel leaders as early as next week.

Long Liberal rule ends

Serpa: dogged by party's alleged drugs links

Mr Pastrana defeated Horacio Serpa, the candidate of the Liberal Party of the outgoing President, Ernesto Samper, by five points, ending a 12-year run of Liberal Party presidents.

The Liberals were harmed by allegations that they received millions of dollars from drugs barons but the party retains its hold on Congress.

Quick count

Mr Pastrana, who was supported by many business people, won just over 50% of the vote, compared with 46.5% for his rival.

It took less than three hours to count more than 95% of all votes, although in areas affected by guerrilla violence, the final result will not be known for several days.

The BBC Latin America correspondent says the uncounted votes will not significantly affect the result.

Voting was cancelled in 59 towns after guerrilla attacks.

Turnout was the highest for a presidential election in years, despite some voters staying at home to watch live World Cup football coverage.