The government plans to deploy 93,000 police officers to prevent unrest during the protest, which is expected to bring much of Peru to a standstill.

The strike was called by Peru's biggest labour unions, which say some 300,000 people will rally in the capital, Lima.

Transport in Peru is already in crisis because a top airline has been grounded at a time of peak demand from tourists.

The Aero Continente airline was banned from flying on Monday after the government alleged its planes were not insured and the US announced it was investigating the firm for ties to the drug trafficking trade.

The ban has left hundreds of tourists stranded, many of them football fans who were hoping to watch South America's biggest international tournament, the Copa America, which is being hosted by several Peruvian cities this year.

Aero Continente's chief has denied the allegations and accused rivals of blackening his firm's name.

Infiltration fears

The organisers of Wednesday's strike say they want better wages and an end to President Toledo's free market economic policies.

More than 150 unions - from teachers to construction workers - have signed up for the protest.

A leader of the biggest group, the communist-led General Workers Union of Peru, said the government might attempt to discredit the strike by inciting violence and blaming it on the unions.

"We're responsible for our actions, but we can't be responsible for any aggression on the part of the forces of repression or any infiltrators," Jose Gorriti told Agence France Presse news agency.

But Peru's government says army and riot police units have been enlisted because of fears the demonstrations might be infiltrated by guerrillas from outlawed Marxist rebel army, the Shining Path.

Corruption scandals have sent President Toledo's approval plummeting since he took office in 2001.