Bashir was in Chad last weekend for a meeting of Sahel and Saharan African leaders. Tiina Intelmann, the president of the assembly of state parties to the Rome Statute of the ICC, said it was regrettable he wasn't apprehended despite two outstanding arrest warrants.
"I call upon the government of Chad to respect and fully comply with its Rome Statute obligations and I also renew my appeal to states parties and others in a position to do so to join efforts to prevent instances of non-cooperation," she said in a statement.
Chad is a party to the statute that created the ICC.
"The assembly had repeatedly expressed concerns regarding the negative consequences which such failure to comply had on the court's capability to carry out its mandate," the ICC stated.
The British government expressed similar concerns early this saying, saying last weekend's visit by Bashir is his third to Chad without an arrest.
Bashir is wanted by the ICC for crimes committed during the genocide in Darfur.