Poland's Foreign Minister has been caught on camera appearing to tell a Ukrainian protester to support the deal because otherwise, "you'll have martial law, you'll have the army. You will all be dead."
The exclusive clip was filmed by ITV as Radoslaw Sikorski left negotiations, which had been struggling to come to an agreement as Kiev itself has been ripped apart by violent demonstrations and seemingly brutal police retaliation.
Asked by ITV News Europe Editor James Mates if he had managed to convince the opposition Mr Sikorski appeared to reply: "I don't know."
In a further development, ITV's Europe Editor then tweeted he had had confirmation from Mr Sikorski that interior ministry troops were being readied.
The news comes after Ukrainian president Viktor Yanukoyvch and opposition leaders agreed to hold early presidential elections after all-night crisis talks.
Presdient Yanukovych has also bowed to pressure from the protesters, agreeing to a national unity government and to constitutional changes that will reduce the powers of the president.
Polish FM @sikorskiradek confirms to me threat of martial law was real "To my knowledge interior ministry troops were being readied"— James Mates (@jamesmatesitv) February 21, 2014
The talks and eventual agreement were mediated by EU foreign ministers such as Mr Sikorski, a former journalist turned politician.
The demonstrations have been marked by brutality as thousands took to the streets in escalating violence, which ha seen the Ukrainian health ministry put the number of people killed at 77, although opposition figures agree the figure is over 100.