A pro-Tamil Tiger Web site reports the Sri Lankan rebels could withdraw from a ceasefire with the government if the European Union bans the organization.
The Tamilnet Web site on Saturday quotes the leader of the rebel group's political wing S.P. Thamilselvan as saying the Tigers would be "forced to reconsider the relevance" of the existing ceasefire.
Last week, European media reported the EU is expected to add the Tamil Tigers to a list of terrorist organizations.
In related developments, the Tamil rebels say they are considering a proposal to attend talks in Norway about the role of truce monitors.
Acting as a mediator between rebels and Sri Lanka's government, Norway has asked both sides to discuss the security of European monitors in the region.
Visiting Norwegian envoy Jon Hanssen-Bauer announced the invitation on Saturday after meeting with Tamil Tiger leaders in the northern town of Kilinochchi. He said the talks would be held June sixth through eighth in Oslo.
It is not clear if Sri Lanka's government has accepted the invitation.
Earlier this month, Tamil Tigers attacked navy boats in a battle that killed sailors and rebels. The Tigers have warned truce monitors to stay off navy vessels, saying they will not be responsible for the consequences of any future attacks.
A 2002 ceasefire agreement between the government and Tamil rebels has been deteriorating amid an upsurge in violent clashes.
Rebels have been fighting for more than two decades to establish a separate homeland for Sri Lanka's ethnic minority Tamils.