The ambassadors of Norway, Japan and the European Union (EU) flew north to rebel political headquarters at Kilinochchi to see the leadership of the Liberation Tigers of Tamil Eelam (LTTE).
Norwegian embassy spokesman Tom Knappskog said the diplomats would "stress the importance of taking the process forward to further meetings, of building deeper confidence and ultimately of realising substantive progress on the peace process".
Diplomats said the ambassadors representing the co-chairs of the peace process would urge the LTTE to attend the three-day truce talks despite renewed tensions.
"The co-chairs are concerned about the government of Sri Lanka's and LTTE's preparations for the second round of ceasefire talks scheduled for later this month in Geneva and the important implications that the outcome of that meeting will have for the wider peace process", an EU statement said.
The ambassadors were expected to convey government guarantees of safe passage for the Tigers, diplomats said.