BOGOTA, Colombia (AP) _ Economist Cesar Gaviria became president of Colombia Tuesday and swore he would make no concessions in the country's war against drug traffickers.

In his inaugural address, the 43-year-old Gaviria proposed creating an international court to try drug traffickers. He said fighting drugs should be an international effort, not just a Colombian one.

The new president asked the United States and Western European countries to remember that this nation of slightly more than 30 million people is not a wealthy country, and to lower trade barriers to help it finance the drug war.

He also said the United States and other countries must do more to cut consumption of cocaine.

''No success is possible if the consuming countries do not achieve a substantial reduction in demand,'' he said.

Heavy security was in effect. Helicopter gunships circled Bogota, the capital city of more than 6 million. Anti-aircraft guns aimed at skies over the presidential palace. Thousands of troops backed by armor patrolled streets.

Gaviria and invited dignitaries sat behind bullet-proof glass. Vice President Dan Quayle represented the United States among 88 foreign delegations.

Gaviria became the candidate of the governing Liberal Party and won May elections after the first candidate, Sen. Luis Carlos Galan, was shot to death by drug lords in August 1989, leading to a government crackdown that continues. ''Drug trafficking is the main threat against our democracy. We will fight it without concessions,'' Gaviria said.

''There is no other way to eradicate from Colombian life the mass murders, the hundreds of deaths from car bombs, the children killed on Mother's Day.''

Two car bombs in Bogota last Mothers Day, May 18, killed 18 people.

''No country in the history of humanity has paid such a high price as Colombia in confronting international crime,'' Gaviria said.

Gaviria, a small, slender man who formerly served as treasury minister, took office for a four-year term, succeeding President Virgilio Barco.

As a congressman and Cabinet minister, he gained a reputation as an efficient administrator and a shrewd negotiator.

Gaviria cautioned on Tuesday that extradition of suspected traffickers to the United States - the fate the drug lords here fear most - cannot be the only weapon or the main strategy in Colombia's fight against the cocaine cartels.

But he didn't rule out continued extraditions. In the last year Colombia has extradited 22 trafficking suspects to the United States and has 15 more waiting to be be extradited.

The government took no chances Tuesday despite a cease-fire purportedly declared by drug traffickers last month.

The Bogota daily newspaper El Espectador said blood types of visiting dignitaries and heads of state were noted to ensure ample blood supplies if needed.

Four armored U.S. Blackhawk helicopters equipped with missiles accompanied Quayle's helicopter from the airport to an army base.

Gaviria inherits a nation weary of its fight with terrorists and drug traffickers and looking for an end to the violence.

Barco, who was prohibitied by the constitution from running again, received international praise for launching the government's war against drug traffickers. He will reportedly become Colombia's next ambassador to Britain.

Of the major candidates, Gaviria took the strongest stand in support of a continued hard line against the Medellin and Cali cocaine cartels, which are believed to supply 80 percent of the cocaine reaching the United States.

Since the crackdown began a year ago, police have blamed drug traffickers for exploding about 300 bombs throughout Colombia and killing about 500 people.

Gaviria has said another way to solve Colombia's problems is to increase political participation of the left and other minority parties.

In naming his Cabinet on Monday, he appeared to be doing just that.

The new ministers include five members of opposition parties, including the M-19, a former leftist guerrilla group that signed a peace treaty with the government in March.