Reuters reports, citing sources familiar with the matter
This feeds into a similar story reported by The Telegraph earlier in the day here.
Essentially, the EU is going to threaten legal action against the UK if the talks later today do not provide them with the reassurance needed that the UK will not break the terms set out by the Brexit withdrawal agreement.
So far, the pound is keeping more resilient in all of this with cable still resting at 1.3010 and EUR/GBP holding just below 0.9100 still.