Mrs Moscoso, the country's first woman leader, said her government would manage the canal responsibly and efficiently after the US withdrawal at the end of the year.

"My government intends to increase the autonomy of the canal so it may operate without any partisan political influence," she told a crowd of 25,000 people in the national stadium.

"Next 31 December at noon, we will have finally and forever achieved our true independence."

Venezuelan President Hugo Chavez offers congratulations

Mrs Moscoso, the 53-year-old widow of former Panamian President Arnulfo Arias, promised a "war on poverty and social injustice" and criticised the outgoing administration for its performance on education and health.

"This is the reality of our country today," she said. "This is the reality that we must change, and my commitment is to this change."

The swearing-in ceremony was delayed by several hours after parliament took longer than expected to swear in its own new members.

Representatives from more than 40 countries attended, including the US special envoy to the Americas, and heads of state from Central and South America.

Canal security

In an interview with the BBC before being sworn in, Mrs Moscoso gave assurances that Panama would be able to guarantee the canal's security.

One of the world's most important waterways

She said no foreign troops would be allowed to remain on Panamanian soil after the last US soldiers pulled out at the end of the year.

But correspondents say Washington is concerned at Panama's ability to maintain security on its southern border, where there have been numerous incursions by Colombian drug traffickers and guerrillas.

The zone around the canal has been under US control since 1903, after the US backed Panama's independence from Colombia.

Election victory

Mrs Moscoso, a teacher's daughter who has never held elective office, inflicted a crushing defeat on outgoing President Ernesto Perez Balladares in May, winning 45% of the vote.

Mr Perez Balladares chose parliament for his last speech

He refused to attend her swearing-in ceremony, accusing her of being rude.

Instead, he delivered his outgoing speech before parliament on Tuesday.

Mr Perez Balladares led a steady economic recovery during his five-year term, but has seen his popularity decline since last August.

His final day in office was marked by student protests against his economic reforms.