Jeremy Browne, the British minister responsible for consular affairs, warned that the activity of al-Qaida in the Islamic Maghreb, al-Qaida's North African affiliate, and the threat of kidnapping were endangering the lives of British nationals.
"We currently advise against all travel to parts of Mauritania, Mali and Niger," he said in a statement.
Two Frenchmen kidnapped last week in the capital of Niger were killed following a French rescue effort. While no group claimed responsibility for the kidnapping, the French government said it believed AQIM was behind the incident.
Seven foreign nationals kidnapped from Niger in September are still being held, Browne added. The British government issued a travel warning Wednesday for Niger, citing the AQIM and kidnapping threat.
AQIM in July announced that it beheaded Michel Germaneau after an attempt by French authorities to rescue the 78-year-old French engineer in Mali. Germaneau was kidnapped in April by AQIM in the northern Niger desert near the border of Mali and Algeria.
Algerian forces are said to be waging a major counter-terrorism offensive against AQIM. Moroccan officials said last week that they arrested 27 people who were part of an al-Qaida cell plotting a terrorist attack in the country.