The US has reaffirmed support for Colombia's efforts to halt illegal drugs production and its civil war, but has given a warning on human rights abuses.

The remarks came from Secretary of State Colin Powell, who arrived in the capital Bogota on Tuesday for talks with the country's new President Alvaro Uribe.

He came to power in August pledging to take a hard line against leftist guerrillas, and to suffocate the coca production revenues they rely on.

However human rights groups have criticised tough new measures he has brought in, including curfews, restrictions on movement and search and arrest rights.

Increased US aid to Colombia includes 72 new helicopters

"There will be a big expectation that, as the Colombian armed forces and the Colombian police are strengthened to deal with this problem, there can be no tolerance for abuse of human rights of the kind that has been seen in the past," Mr Powell said.

He said it remained to be seen whether the right-wing paramilitary group the AUC - which is accused by some of the worst abuses - would renounce its "extralegal, unconstitutional actions".

The AUC, which is on the US State Department terrorism list along with two other Colombian factions, - announced a unilateral ceasefire last week.

More money

He confirmed that US assistance to Colombia was expected to rise from $300m to $430m, part of a massive rise in funding since 2000. It will also get $98m to help protect a lucrative oil pipeline.

Colombia is the third largest recipient of US aid after Israel and Egypt, but US priorities had appeared to shift following its "war on terror" declared after the 11 September 2001 attacks.

"It seemed a good time to reinforce our commitment to Colombia, to review their efforts on narcotrafficking and narcoterrorism," Mr Powell told reporters.

In an earlier interview with a Colombian newspaper, Mr Powell said he hoped to demonstrate US solidarity in efforts to tackle "those terrorist elements within Colombian society who are trying to destroy the dream of the Colombian people to have a democracy that gives them a society that is safe."

The authorities' shaky hold on order was underlined by the huge security presence that surrounded Mr Powell's arrival at Bogota's military airport.

Coca clampdown

Two helicopters hovered overhead while more than 50 police on motorcycles and hundreds of soldiers guarded the route to his hotel.

Colombia has greatly extended efforts to eradicate coca - the plant that is processed to make cocaine - through aerial spraying initiatives, but Mr Powell said eradication had not yet outstripped new planting.

One of the problems with this type of eradication is that the defoliant used destroys plants indiscriminately - often removing legitimate sources of income for farmers.

BBC correspondents in the region have even discovered instances in which coca - a tough mountain plant - survived the spraying better than edible crops.