Chad refuses to arrest Sudan's al-Bashir
Omar al-Bashir has travelled abroad only to countries that are not ICC members since he was first charged in connection with violence in Sudan's Darfur region in 2009.
The ICC has no police force and depends on member states to enforce its orders.
Chadian officials said they would not detain al-Bashir. "Bashir will not be arrested in Chad," said Chadian Interior Minister Ahmat Mahamat Bachir.
The mayor of N'djamena, Chad's capital, also gave the president a warm welcome by presenting him with a key to the city upon his arrival.
"Chad and Sudan had a problem in the past. Now this problem is solved. We are brothers," al-Bashir told reporters in N'djamena.
Sudan-Chad relations more important
Sudan's government spokesman, Rabie Abdel Attie, said Sudan-Chad relations were more important than the fact Chad is a party to the ICC.
"I don't think Chad will do anything to harm the president. There is an agreement to end hostilities," he said.
Besides participating in a summit of the Community of Sahel-Saharan States, the Sudanese president is also expected to discuss bilateral relations, including a January agreement between Sudan and Chad to end hostilities and stop supporting each other's rebel groups, Abdel Attie said.
Human Rights Watch urged Chad to arrest al-Bashir. "Chad risks the shameful distinction of being the first ICC member state to harbour a suspected war criminal from the court," said HRW's Elise Keppler. "Chad should not flout its obligations to arrest al-Bashir if he enters Chad."
Abdel Attie didn't respond to questions about guarantees from Chad for the president's safety. But he indicated that the mutual benefits Sudan and Chad get out of the end-of-hostilities agreement trumps the desire to arrest al-Bashir.
"I don't think [either] country will breach this agreement," he said, adding that there are now joint Sudanese-Chadian military units patrolling the borders. The arrest warrant "is not a subject to discuss between the two countries."
Keppler said the political deal between Chad and Sudan was "no justification for shielding alleged war criminals."
Chad previously denied the leader of a major Darfur rebel group entry into its territories. According to the joint agreement, both countries have to stop providing operational ground for each other's rebel groups.
Darfur's ethnic African rebels rose up in 2003, accusing Sudan's Arab-dominated central government of neglect and discrimination. UN officials estimated 300,000 people died and 2.7 million were displaced.
Many Darfur rebels come from tribes that overlap the border between the countries, and some have bases in Chad, which for years had strained relations with Sudan.
In February, the two countries pledged to deny support for each other's rebels and to monitor borders. Many observers praised it as a boost for peace prospects in Darfur.
Al-Bashir was charged in March 2009 with five counts of crimes against humanity and two of war crimes for allegedly orchestrating atrocities in Darfur. Last week, the ICC charged him with three counts of genocide, the first time the world's first permanent war crimes tribunal has issued genocide charges.