John Bolton, the US national security adviser, has courted controversy by flashing a note reading “5,000 troops to Colombia” during an announcement of fresh sanctions on Venezuela.

The hawkish former UN ambassador held his notepad in such a way that the handwritten line was clearly visible, but did not mention plans to deploy US forces to the neighbouring country during his news conference on Monday.

Mr Bolton announced sanctions on Venezuela’s state-owned oil company, PDVSA, designed to ratchet up pressure on embattled president Nicolas Maduro amid an ongoing crisis in the Latin American nation.

Donald Trump was the first to recognise national assembly leader Juan Guaido as interim president following his assertion of legitimacy last week. The UK and a string of other countries followed suit in backing the 35-year-old.

Sanctions to block $7bn (£5.3m) in PDVSA’s assets and $11bn (£8.4bn) in exports will mean Mr Maduro can “no longer loot the assets of the Venezuelan people”, Mr Bolton said during the briefing.

Venezuela protests: thousands rally against government Show all 18 1 /18 Venezuela protests: thousands rally against government Venezuela protests: thousands rally against government Protesters clash with the Bolivarian National Police during a demonstration against the government of the Venezuela and president Nicolas Maduro in Caracas on 23 January 2019 EPA Venezuela protests: thousands rally against government Demonstrators cheer as Venezuela's National Assembly head Juan Guaido declares himself the country's "acting president" at a rally in Caracas AFP/Getty Images Venezuela protests: thousands rally against government Opposition supporters take part in a rally against Venezuelan President Nicolas Maduro's government REUTERS Venezuela protests: thousands rally against government Opposition supporters take part in a rally against Venezuelan President Nicolas Maduro's government in Caracas REUTERS Venezuela protests: thousands rally against government Juan Guaido, head of Venezuela's opposition-run congress, declares himself interim president of the nation until elections can be held during a rally in Caracas demanding leader Nicolas Maduro's resignation AP Venezuela protests: thousands rally against government Opposition supporters carry letters to form the word "Democracy" while taking part in a rally against Venezuelan President Nicolas Maduro's government REUTERS Venezuela protests: thousands rally against government Police watch over marching anti-government protesters in Caracas EPA Venezuela protests: thousands rally against government A vehicle is overturned as opposition demonstrators block a road during a protest against the Venezuelan government AFP/Getty Images Venezuela protests: thousands rally against government A National Police officer fires rubber bullets during a protest against Venezuelan President Nicolas Maduro's government in Caracas REUTERS Venezuela protests: thousands rally against government A demonstrator throws back a gas canister while clashing with security forces during a rally against Venezuelan President Nicolas Maduro's government in Caracas REUTERS Venezuela protests: thousands rally against government Security forces look on after clashing with opposition supporters participating in a rally against Venezuelan president Nicolas Maduro's government REUTERS Venezuela protests: thousands rally against government Demonstrators during a protest against the government of Nicolas Maduro at Plaza Altamira in Caracas Getty Images Venezuela protests: thousands rally against government Demonstrators during a protest against the government of Nicolas Maduro at Plaza Altamira in Caracas Getty Images Venezuela protests: thousands rally against government epa07313731 Opponents of Chavism demonstrate against the Government of President Nicolas Maduro in Caracas, Venezuela, 23 January 2019. Chavists and opponents are again demonstrating in the streets of the country to support or question the legitimacy of the head of state, which the Parliament and a large part of the international community do not recognize. EPA/CRISTIAN HERNANDEZ CRISTIAN HERNANDEZ EPA Venezuela protests: thousands rally against government Riot police clash with opposition demonstrators during a protest against the government of President Nicolas Maduro on the anniversary of the 1958 uprising that overthrew the military dictatorship, in Caracas on January 23, 2019. - Venezuela's National Assembly head Juan Guaido declared himself the country's "acting president" on Wednesday during a mass opposition rally against leader Nicolas Maduro. (Photo by YURI CORTEZ / AFP)YURI CORTEZ/AFP/Getty Images YURI CORTEZ AFP/Getty Images Venezuela protests: thousands rally against government The remains of a statue of Venezuela's late President Hugo Chavez is seen hanging from a pedestrian bridge after it was destroyed in San Felix, Venezuela REUTERS Venezuela protests: thousands rally against government Riot police on motorcycles clash with opposition demonstrators during protests in Caracas AFP/Getty Images Venezuela protests: thousands rally against government Supporters celebrate Juan Guaido declaration that he is Venezuelan president EPA

The Pentagon has not announced any plans to send US troops to Colombia. When asked to explain the words in Mr Bolton’s notepad, the White House said that “as the president has said, all options are on the table”.

Colombia said it could not explain the provocative note. Foreign minister Carlos Holmes said he did not know the “importance and reason” for Mr Bolton flashing it and added that Colombia planned to continue “acting politically and diplomatically” in relation to its neighbour.

Bogota has recognised Mr Guaido’s claim to the presidency.

Mr Maduro described the fresh sanctions as “criminal” and accused the US of robbing Venezuelans of oil wealth that was rightfully theirs. He told Mr Trump during a televised address to take his “hands off Venezuela”.

"We will provide the reciprocal and convincing response needed to defend Venezuela's interests in due time," he added, pledging to defend Citgo, PDVSA's US refining subsidiary, which he accused Washington of trying to steal.

Falling oil revenue as a result of the restrictions may hamper Caracas' ability to import basic goods like food and medicine, further exacerbating the humanitarian crisis that has gripped the country.