UK Foreign Secretary Dominic Raab has said the shooting of protesters in Myanmar is "beyond the pale".
Mr Raab's words came following reports that two anti-coup protesters in Mandalay had been killed by police.
One man was shot in the head and died at the scene while a second man was shot in the chest and died in hospital, according to local media.
Twenty-two people were also injured in the city's protest, according to Ko Aung, a leader of the Parahita Darhi volunteer emergency service.
Mr Raab wrote on Twitter: "The shooting of peaceful protesters in Myanmar is beyond the pale.
"We will consider further action, with our international partners, against those crushing democracy and choking dissent."
There have been protests in Myanmar since the military took power earlier in February, claiming there had been "huge discrepancies" in last November's election.
Britain, the US, Canada and New Zealand have announced limited sanctions, with a focus on the military leaders behind the coup.
The protesters have been demanding the restoration of the elected government and the scrapping of a 2008 constitution that has given the army a major role in politics since decades of direct military rule ended in 2011.