Boris Johnson held a Covid-19 press conference today amid concerns over the spread of the Indian strain of the Coronavirus.
The PM said today that "there are some important unknowns" about the Indian variant.
"We believe this variant is more transmissible... but we don't know by how much," he said.
"If the variant is significantly more transmissible, we're likely to face some hard choices" when it comes to easing restrictions. He added this could have an effect on any decision to ease measures in June.
' I have to level with you that this new variant could pose a serious disruption to our progress and could make it more difficult to move to Step 4 in June" said Boris.
Asked how likely it was that Step 4 could be delayed he added: 'The truth is at this stage we simply can't say for certain.'
The PM said the plan remains for businesses including restaurants, theatres, cinemas and restaurants to reopen on Monday and he will not delay the roadmap out of lockdown at this stage.