Demesmaeker, a member of parliament's delegation to the EU-Ukraine parliamentary cooperation committee has called for a "three dimensional approach of defence, diplomacy and development" to resolving the year long conflict.
The Belgian deputy last week accompanied a team of volunteers delivering aid to military personnel and refugees in the Debaltseve region of eastern Ukraine.
The ECR's human rights spokesperson said, "I saw with my own eyes the severe violations of the Minsk II ceasefire agreement. Ukrainian positions are under constant hostile fire."
Demesmaeker said more must be done to help civil society in Ukraine and that "it must be made clear to Russian president Vladimir Putin that he cannot get his own way".
The Flemish deputy said economic sanctions are having an effect and he "favours more sanctions if aggression continues".
"The intensity and aggressiveness during attacks, even while the retreat was ongoing, showed the intention to cause maximum casualties"
On supplying arms to the Ukrainian rebels, the ECR deputy described himself as a pacifist but said, "Ukraine should be able to defend itself". He noted that if supplying munitions did proceed, "weaponry would have to get into the right hands, not breakaway militias and it was not clear who would end up getting the weapons".
He told a press conference held in parliament that it was his view that casualty figures were higher than official estimates. He said, "The intensity and aggressiveness during attacks, even while the retreat was ongoing, showed the intention to cause maximum casualties."
Demesmaeker was extremely critical of the role of the European external action service and foreign affairs chief Federica Mogherini, saying the EU's response showed "a lack of insight as to what Putin wants".
The Flemish deputy, who also serves on parliament’s foreign affairs committee (AFET) was particularly critical of Mogherini's 'Issues paper with Russia' which he said had "no strategy at all" to achieve the goals underpinning it.
He said the lack of action to date demonstrated "a lack of initiative that contributes to Putin's aggression" and that, "the EU must invest more in real European diplomacy". The deputy added that, "Putin respects strength and when he look to Europe he sees a weak partner."
The Belgian MEP noted that, "Putin wants Russia to be a superpower and what we are offering is a new dialogue. Europe doesn't exist in Putin's eyes".
The AFET committee member warned that altering Putin's outlook with regards to expansion in eastern Europe is a long-term project "and change would have to come from within" Russia itself. Demesmaeker called for Europe "to be more visible" in the crisis and examine its own defences in the east in light of confrontation as "Putin will try to further destabilise the region".
He described what he saw in eastern Ukraine as a "humanitarian crisis that has been underestimated", highlighting that starvation and a lack of medicines were apparent and that even "Ukrainian authorities don't realise how bad the crisis is".
Demesmaeker concluded by saying it remains to be seen if the ceasefire will hold and called for a large demilitarised zone to be put in place, as well as much more pressure to be put on EU member states to provide humanitarian aid.