South Korea's foreign ministry said Monday it has raised its travel warning for Gabon, amid rising tension in the African country due to controversy surrounding a reportedly fraudulent election.

The Ministry of Foreign Affairs said it has imposed a "yellow" alert on the country, a notch higher from the previous "blue," adding its security has deteriorated significantly due to the political instability.

A yellow alert is the second-highest of a four-tier travel warning system under which people are advised to refrain from visiting the area.

The ministry also requested South Koreans already residing in the country to be more cautious about their safety. (Yonhap)