A new Covid strain, named Mu, has been designated a variant of interest by the World Health Organisation (WHO).
Mu, or B.1.621, was first identified in Colombia and cases have been recorded in South America and Europe.
The WHO's weekly bulletin on the pandemic said the variant has mutations suggesting it could be more resistant to vaccines - as was the case with Beta.
But this is not conclusive, and scientists said more studies would be needed to examine this further.
It was first identified at the start of the year, and a large number of cases have since been found in Colombia, where it now accounts for 39 per cent of Covid infections.
Near neighbour Equador has a 13 per cent prevalence, the WHO said.
The latest bulletin said: "Since its first identification in Colombia in January 2021, there have been a few sporadic reports of cases of the Mu variant and some larger outbreaks have been reported from other countries in South America and in Europe.
"Although the global prevalence of the Mu variant among sequenced cases has declined and is currently below 0.1%, the prevalence in Colombia (39%) and Ecuador (13%) has consistently increased.
"The epidemiology of the Mu variant in South America, particularly with the co-circulation of the Delta variant, will be monitored for changes."
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There are currently four coronavirus variants of concern, as deemed by the WHO, with the Alpha variant - first recorded in Kent - seen in 193 countries, Beta in 141, Gamma in 91 and Delta in 170 countries, while Mu is the fifth variant of interest.
The news comes just hours after Taoiseach Micheal Martin announced plans to end most restrictions in Ireland.
Mr Martin said sectors that have remained shuttered “can begin to hope again” as he announced the major scaling back of legal restrictions on “people’s personal freedoms.”
He pledged that we would “rebuild our economy and society” as we confirmed the country’s exit roadmap with all restrictions to go on October 22.
The plan has revealed people will get back to the office, can dance again and greater numbers can gather at mass gatherings.
He hailed the country’s efforts in an emotional speech and declared: “We kept our head as a country.
“We stuck together, we followed the best advice, we did what we were asked and we looked out for each other.
“Because of the effort of our vaccination team and because you have stepped up to the mark and taken the vaccine when it was offered, we are now entering a whole new phase of the pandemic.
“We have weathered many storms, we’ve borne many ordeals, we’ve faced down many threats and we have seized many opportunities.
“We will rebuild our economy and renew our society.
“We will do these and all the other things, with renewed energy and determination, with personal freedoms restored and our country, we hope, emerging from this most extraordinary period in our history.”
