Theresa May left Thursday for the G20 summit in Argentina in what will be the first-ever visit by a British prime minister to Buenos Aires.
The trip should give May the chance to explain the Brexit divorce deal to other global leaders and set out Britain's plans to engage with the wider world.
"She will deliver the message that as we leave the EU, the UK will be an active and open global trading partner," her spokesman told reporters.
She will also set out Britain's commitment to tackling climate change.
However, she faces risks in leaving the domestic battlefield in the middle of a fight to stop the Brexit deal collapsing into chaos -- which could trigger her downfall.
The chance to appear on the global stage would normally be a welcome distraction but the G20 comes at an awkward time for May.
She has limited days left to convince a hostile parliament to back the agreement she has struck with Brussels -- with anti-deal Brexiteers in her own Conservative Party sniffing for blood. MPs vote on December 11.
British premiers on foreign visits are customarily dogged by questions about domestic issues back home.
She will be the first serving British premier to visit the Argentine capital. The only previous visit a British prime minister ever made to Argentina was in 2001 when Tony Blair crossed the border from Brazil for two hours.
Relations between Britain and Argentina, who went to war in 1982 over the Falkland Islands, have improved since the election of centre-right President Mauricio Macri in December 2015.
Ties soured under his nationalist leftist predecessor Cristina Kirchner and her emotional demands for control of Britain's Falklands overseas territory.
Facundo Rodriguez, an Argentinian international lawyer specialised on the Falklands sovereignty dispute, told AFP: "Theresa May's is a relevant visit that will strengthen the new but not novel way the local administration has adopted to build a relationship with the UK."
The visit follows Tuesday's announcement of a second monthly air link between the Falklands and Argentina.
"Building closer links represents a shared goal," said Britain's Foreign Office.
Rodriguez said the Falklands would be the "elephant in the room".
It is "not a convenient issue to discuss in such a crucial time for the Brexit bill", he said. "We shouldn't expect anything about the substantive issue of sovereignty."