BOGOTA - Russia will face consequences if it meddles in the US legislative election this year, Secretary of State Rex Tillerson has said.

CIA Director Mike Pompeo warned last month that he does in fact expect Moscow to try to interfere, as US intelligence agencies insist it did in the 2016 presidential election to help Donald Trump beat Hillary Clinton.

Tillerson, speaking to Fox News during a tour of Latin America, said "there's a lot of ways that the Russians can meddle in the elections, a lot of different tools they can use." "And we are seeing certain behaviors. There are a number of important elections in this hemisphere this year, and leading up to the US in 2018," Tillerson said. "I think it's important we just continue to say to Russia 'Look, if you think we don't see what you're doing, we do see it and you need to stop. If you don't, you are going to just continue to invite consequences for yourself.'"

He added, though, that if Moscow decides to meddle in an election, "it's very difficult to preempt it."

Special prosecutor Robert Mueller and US lawmakers are probing the Russian meddling in the 2016 presidential election, specifically whether the Trump campaign colluded in that effort and whether Trump has tried to obstruct justice by hindering the investigations.

Tillerson's first official foray to the region began badly last week, when his arrival in Mexico was overshadowed by President Donald Trump's latest attack on US allies.

But as he prepared to leave Colombia on Tuesday after six days of visits to Mexico, Argentina and Peru, he had conducted what he described as positive and successful meetings with top leaders.

Latin America's democracies support Washington's opposition to the Venezuelan regime of Nicolas Maduro, whom they accuse of subverting the constitution to cling to power illegitimately.

And the countries Tillerson visited - whatever Trump may have said about them "laughing at" Washington while pocketing US aid - renewed their pledges of support to fight drug trafficking.

"I don't think that President Trump is referring to Colombia, because Colombia is not laughing at the US," President Juan Manuel Santos said at a joint news conference with Tillerson.

"There would be no supply if there's no demand and no demand if not for supply, and Colombia does not laugh at this very important issue because it's a matter of national security," Santos said.

"We have lost our best leaders, journalists, judges, policemen in this war against drugs."

Santos said no country had suffered more than Colombia during a four-decade war on drugs, which in his country also fed and was fed by civil conflict with leftist rebels.

If Tillerson has had any more success than Trump, with his threats and harsh criticism, in winning over foreign leaders, it may be because he accepts that Washington shares responsibility.

In Colombia, he agreed with Santos that there would be no supply of drugs without the demand of the US market, and in Mexico he acknowledged that smuggled US guns fuel cartel violence.

But while he pushed for and welcomed cooperation, he also left behind a note of caution, warning that as Colombia at last emerges from civil war, its production of cocaine is soaring. "One of the things that's important about this relationship is that we are so close, we can speak openly and frankly about things of concern," Tillerson said, standing alongside Santos.

"The rapid increase in cultivation was an intended consequence of the peace and - as the president has described it - now it's now the long process of reversing those trends." Tillerson would not be drawn on Trump's threat to cut aid if countries fail to halt the northward flow of drugs, but he warned "our expectation is that Colombia will make significant progress."

The other main theme of Tillerson's trip was the looming catastrophe in Venezuela, where Maduro is pressing ahead with plans to seek re-election under an electoral system controlled by his regime.

Earlier on Tuesday, Tillerson had met President Pedro Pablo Kuczynski of Peru, the country that helped set up the Lima Group of like-minded American allies seeking a democratic solution in Venezuela.

The country is gripped by political strife and faces economic catastrophe. More than half a million people have already fled to Colombia, increasing the pressure on its post-war recovery.

Tillerson thanked Peru for its leadership and offered more support in the runup to this year's Summit of the the Americas, which Kuczynski will host in April on the theme of fighting corruption.

The US envoy received strong political backing during the trip for Washington's tough stance on Venezuela. All the capitals he visited have vowed not to recognize Maduro's "illegitimate" poll.

But discussion will continue on the idea of a US embargo on Venezuelan oil exports. This would heap huge pressure on the regime, but might trigger a destabilizing total economic collapse.

Tillerson for his part acknowledged that more thought would have to go on how such a measure would affect the long-suffering Venezuelan people - and also US refineries reliant on Venezuelan exports.

On Wednesday, Tillerson will stop off in Jamaica on his way back to Washington, for talks on how the Caribbean region could cope if its subsidized flow of oil from Venezuela comes to a halt.