Queen Elizabeth Park shares a border with DRC and its renowned Virunga National Park, where armed groups are believed to operate.
The UK government on Wednesday warned its citizens to avoid travel to a popular Ugandan park where two tourists, including a Briton, and their local guide were killed in an attack blamed on a notorious militia group.
The trio were targeted on Tuesday by gunmen as they were on safari in Queen Elizabeth National Park in southwestern Uganda and their vehicle set on fire, police and park officials said.
Britain's Foreign Office said it "advises against all but essential travel" to the park, a tourist magnet where lions are known for their unusual ability to climb trees.
"If you are able to do so safely, you should consider leaving the area."
Uganda's wildlife authority identified the two other victims as a South African holidaymaker and a Ugandan guide.
Police blamed the attack on the Allied Democratic Forces (ADF), a rebel militia based in the neighbouring Democratic Republic of Congo (DRC) that is affiliated to the so-called Islamic State group.
"Our joint forces responded immediately upon receiving the information and are aggressively pursuing the suspected ADF rebels," police spokesman Fred Enanga said.
Queen Elizabeth Park shares a border with DRC and its renowned Virunga National Park, a habitat for rare mountain gorillas, and where armed groups are believed to operate.
In 2019, a US tourist and her safari guide were kidnapped by four gunmen during an evening game drive through the Ugandan park. They were recovered unharmed after a ransom was paid.
The ADF is historically a Ugandan rebel coalition whose biggest group comprised Muslims opposed to veteran President Yoweri Museveni.
Established in eastern DRC in 1995, the group became the deadliest of scores of outlawed forces in the deeply troubled region.
It has been blamed for massacres, kidnappings and looting, with a death toll estimated in the thousands.
In June, ADF fighters killed 42 people including 37 students in a high school in western Uganda near the border with DRC.
Tourism is a top foreign exchange earner in Uganda, contributing almost 10 percent of GDP, according to government figures.
Uganda's wildlife officials said all parks will remain open despite Tuesday's attack.