They also said that they expected Croatia's EU entry talks to start on Thursday as scheduled.
Sanader arrived at EPP headquarters in Brussels on Tuesday to convey assurances that Croatia has met all the requirements for the start of accession talks between Zagreb and Brussels.
"Croatia expects the entry talks to start on 17 March. I am sure that Croatia has met the condition of full cooperation with the ICTY, which the European Council set on 17 March 2004," Sanader told a news conference, with Martens at his side.
Sanader added that Croatia had sent two letters informing the Luxembourg Presidency of the EU that it was fully cooperating with the ICTY and described all what it had done in this field.
"According to our information and all our sources from Croatia, Gotovina is not in Croatia. That is the only and full truth," the Croatian PM said.
Croatia has responded to the 17 December invitation of the European Council, and we are sure that it is fully cooperating with the Hague Tribunal, which is what the Council requested, Martens said.
Martens announced that the EPP would ask the EU Council to decide on opening the talks on 17 March.
We in the EPP, which is the largest group in the European Parliament, are absolutely sure that the Croatian authorities are fully and unreservedly cooperating with the ICTY, and that they are taking comprehensive and far-reaching measures to arrest General Gotovina, Martens said.
He voiced confidence that it was the European Union that had the exclusive right to decide on the matter, regardless of views of some other institutions, non-EU members and individuals.
Therefore we insist that the EU Council decide on the start of the talks, he said.
Croatian authorities can fully cooperate with the ICTY even if they do not locate Gotovina, because they cannot locate him if he is not in Croatia, Martens said in response to a reporter's question.
Sanader added that Croatia did not want a decision on the start of Croatia's entry talks to cause divisions within the Union. He thanked the EPP for its support to Croatia in its bid to join the EU.
Sanader said he was expecting that conclusions of the EPP foreign ministers would convey full and unreserved support for the start of the accession negotiations on Thursday.
He said that Croatia was sharing Martens's interpretation that full cooperation "means that Croatia is doing its utmost" in the search for the runaway general.
ICTY Chief Prosecutor Carla del Ponte told Luxembourg Foreign Minister Jean Asselborn on Tuesday that Croatia was still not fully cooperating with the tribunal, spokespersons for Del Ponte and Asselborn told Hina.
Del Ponte held an unscheduled meeting with Asselborn in The Hague ahead of the EU's decision on whether or not it would open membership talks with Croatia on March 17.