KAMPALA, Uganda — Rights groups on Monday urged Ugandan authorities to arrest the visiting president of Sudan, who has long been wanted by the International Criminal Court for serious crimes.

Sudan President Omar al-Bashir was welcomed to Uganda Monday by Ugandan President Yoweri Museveni. Sudan’s president is here for a two-day visit.

As a signatory to the ICC treaty, Uganda has an obligation to arrest Omar al-Bashir, who has been indicted by the ICC for alleged war crimes and crimes against humanity in Sudan’s Darfur region.

“Inviting an international criminal suspect to Uganda not only undermines the fight against impunity which Uganda has for long championed but also betrays the concerns and interests of the victims of the most heinous crimes,” six Ugandan rights watchdogs said in a joint statement. “We therefore call upon the government of Uganda to fulfill its obligations under international and domestic laws by arresting and surrendering President Omar al-Bashir.”

Al-Bashir’s presence in Uganda “is an affront to Darfur’s victims,” said the U.S.-based Human Rights Watch. Other African members of the ICC, including Kenya and Nigeria, “have avoided or curtailed such visits by al-Bashir,” said Elise Keppler of Human Rights Watch.

South Africa, however, hosted al-Bashir in 2015 and did not arrest him. The ICC’s finding that South Africa should have arrested al-Bashir prompted South Africa to announce that it would withdraw from the ICC. Some other African countries have called for a mass exit from the ICC treaty, saying the court unfairly targets Africans.

Ugandan authorities say the Sudanese leader is immune from arrest because he is a head of state visiting at the invitation of Uganda’s government.

Uganda’s Museveni has sharply criticized the ICC, calling it “useless” during his inauguration in May 2016, an event that al-Bashir attended.

During al-Bashir’s visit “areas of cooperation will be discussed, including trade and investment, agriculture, regional peace and security as well as international matters of mutual interest,” Uganda’s Ministry of Foreign Affairs said in a statement.

Sudan imports 20 percent of Uganda’s coffee, “the single biggest export market” for one of Uganda’s top revenue earners, according to the statement.

Uganda’s diplomatic ties with Sudan once were frosty, but relations improved after South Sudan gained independence from Sudan in 2011. Uganda, which backed South Sudan’s decades-long war of independence, accused Sudan of supporting rebels opposed to Uganda’s government who operated in northern Uganda.