This was according to a Ugandan official said.
"Kagame is not coming," James Mugume, a senior official in the Ugandan foreign ministry, told AFP, saying the president would be represented by Rwandan Foreign Minister Louise Mushikiwabo.
Mugume gave no indication as to why Kagame – whose government the United Nations accuses of backing DR Congo's M23 rebels, a claim Kigali rejects – had decided not to attend.
Sources in Brazzaville and Kigali said the Republic of Congo's President Denis Sassou Nguesso would fly into the Rwandan capital Saturday afternoon for talks with Kagame. Members of Sassou's delegation had already arrived Friday in Kigali.
Meanwhile DR Congo President Joseph Kabila arrived late morning at Munyonyo resort on the outskirts of Kampala, where the summit will be held.
Ugandan officials had earlier said that both Kagame and Kabila would attend and that without them the summit would be "meaningless".
President Mwai Kibaki of Kenya and Tanzania's Jakaya Kikwete were also in Kampala for the summit, along with host Yoweri Museveni of Uganda, Mugume said.
A delegation from the M23 rebels was also in Kampala, but not at the summit venue, and was expected to hold separate talks with Museveni later in the day.
Kabila and Kagame met on Tuesday and Wednesday, hours after the rebels seized the regional capital of Goma, issuing a joint statement with Museveni calling for the M23 to stop its offensive and pull out of the key eastern city.
The International Conference on the Great Lakes Region (ICGLR) has held multiple summits in recent months on the conflict in eastern DR Congo, but none resulted in a significant breakthrough. – Sapa-AFP