Benita Ferrero-Waldner, the EU's external relations commissioner, said on Monday that the ceasefire was needed as the situation for civilians trapped in the war zone was "very dangerous".
"Approximately 170,000 people ... are being trapped in the northern part of Sri Lanka and neither the Sri Lanka government or the LTTE has until now accepted our appeal," she said.
Ferrero-Waldner said that an EU delegation would travel to the country to push for the ceasefire.
The LTTE made no immediate comment on the ceasefire call.
Kohona said that the separatists were responsible for civilian casualties as they are using them as human shields after the military pushed them back into a tiny area on the northeastern coast.
"They are holding their own people hostage, the international community should recognise this,'' he said.
Red Cross warning
The International Committee of the Red Cross (ICRC) said on Tuesday conditions were getting worse for civilians by the day in the war zone.
The ICRC has helped about 4,000 people leave the area this year.
"Many of these people are forced to shelter in trenches. They are in considerable physical danger after being forced to move from place to place en masse for weeks or even months," Paul Castella, ICRC Sri Lanka mission head, said in a statement.
Meanwhile, a suspected Tamil Tiger suicide bomber blew himself up several metres from the frontline on Monday, the military said.
"A soldier on the frontline in Puthukudiyiruppu observed a military-uniformed man coming towards the [line] and when he moved ahead to search him, the terrorist exploded himself," Brigadier Udaya Nanayakkara, a military spokesman, said.
He said no soldiers were killed or wounded.
The LTTE has been battling government forces, seeking a separate homeland for ethnic Tamils in the north and east of the country.