As many as 200 soldiers were killed in an attack on a Kenyan military camp in Somalia by al Shabaab Islamists last month, according to Somali President Hassan Sheikh Mohamud.
Kenyan authorities have refused to give a death toll following the January 15 raid, which targeted troops working under the African Union Mission in Somalia (AMISOM) near the southern Somali town of El Adde.
Newspaper pictures of coffins draped with Kenyan flags bringing back dead soldiers after the attack increased the disquiet from ordinary Kenyans and the opposition alike over Kenya's continued presence in Somalia.
"When about 200 soldiers who came to help your country are killed in one morning, it is not something trivial," Mohamud told Somali Cable TV, in an interview posted on YouTube on Thursday.
"We have been winning for years and months but that El Adde battle, we were defeated.
Yes, in war, sometimes something that you do not like happens to you," he said.
Kenya sent soldiers into Somalia in 2011 after raids in the border region and kidnappings that threatened the tourism industry in the region's biggest economy and wider regional destabilisation.
It later joined the AMISOM operation.
Al Shabaab's attacks in Kenya have included a raid by gunmen on the upscale Westgate shopping mall in 2013 and a university in Garissa in 2015.
Kenya Defence Forces spokesman, Colonel David Obonyo, denied the number given by the Somali president and questioned the source of the information.
The al Qaeda-aligned militants have been driven out of major strongholds in Somalia by AMISOM and Somali army offensives, but the group still controls some rural areas and often launches guerrilla-style assaults and bomb attacks.
Al Shabaab, which wants to overthrow Somalia's Western-backed government, had initially said it had killed more than 100 soldiers in the attack.