Omar al-Bashir, Sudan's president, has arrived in Beijing for talks with Hu Jintao, his Chinese counterpart.
He arrived in the early hours of Tuesday after a delay that the Sudanese foreign ministry attributed to a change in his flight plan.
Topics expected to come up in Bashir's talks with Hu include Chinese aid to Sudan and problems in Abyei, a disputed border area claimed both by Khartoum and the rival government in the south.
Bashir's meetings with Hu and other senior Chinese leaders are now set for Wednesday, according to the foreign ministry in Beijing.
Bashir is wanted by the International Criminal Court (ICC) for alleged genocide, war crimes and crimes against humanity that occurred in Sudan's western Darfur region, where about 300,000 people have died since 2003.
China is a key supporter of the Sudanese leader, who is the first sitting head of state targeted by an ICC arrest warrant.
China is a major buyer of Sudanese crude oil, and is keen to ensure the partition of Sudan into two states will not descend into fighting that could disrupt supplies and damage Beijing's stake on both sides of the new border.
Bashir and the ICC
Beijing defended the visit, with foreign ministry spokesman Hong Lei saying: "As a friendly country of China, the Sudanese leader's visit to China is quite reasonable."
The spokesman added: "In recent years, President Bashir has made many visits to foreign countries and was warmly welcomed by those countries. He will also be welcomed in China."
"We reserve our opinion on the ICC's prosecution against President Bashir."
He said Bashir's visit would be "conducive to the development of the traditional friendship between China and Sudan, as well as the advancement of the peace process of North-South Sudan" and would touch on Darfur.
The Sudanese leader's visit to China has sparked outrage among rights groups, and earned the reproach of the US State Department.
"We continue to oppose invitations, facilitation, support for travel by ICC indictees," State Department spokeswoman Victoria Nuland said Monday.
"We have a longstanding policy of strongly urging other nations to do the same," she said. "We have urged China to join the international community in its call for Sudan to cooperate fully with the ICC."
'Haven for alleged perpetrators of genocide'
ICC statutes dictate that any member country should arrest Bashir if he visits. China is not a party to those statutes, nor is the United States.
Amnesty International said earlier this month that China risked becoming a "safehaven for alleged perpetrators of genocide" if it hosted Bashir.
The United Nations Security Council voted unanimously on Monday to send a 4,200-strong Ethiopian peacekeeping force to Abyei in a bid to douse tensions.
An estimated two million people died in Sudan's two-decade civil war.
A 2005 peace accord, the Comprehensive Peace Agreement, ended the conflict and allowed for a referendum in January in which the south voted by an overwhelming majority to split from the north.