Nigeria, Nov. 14 -- The Nigerian government has issued a travel advisory, warning citizens to be cautious when travelling through Addis Ababa, Ethiopia, due to its high altitude, which could pose health risks.

In a statement issued on Friday, the Ministry of Foreign Affairs warned that the high altitude could pose a serious risk to travellers with pre-existing cardiovascular and respiratory conditions.

The ministry said at least 16 Nigerians have died due to complications linked to the city's high-altitude terrain but did not provide details.

According to the ministry, Addis Ababa, the Ethiopian capital, sits about 2,355 metres (7,726 feet) above sea level, where lower atmospheric pressure reduces oxygen availability and poses a health...