Britons are being urged against travelling to parts of Nigeria after a series of terrorist bomb attacks left scores of people dead.
At least 143 people were reported to have been killed in the bombings in the northern city of Kano. The radical Islamist group Boko Haram has claimed responsibility for the attacks.
Foreign Secretary William Hague said he was "shocked and appalled" by the violence.
Authorities enforced a 24-hour curfew in the city, with many people remaining home as soldiers and police patrolled the streets and set up roadblocks.
In the wake of the attacks, the Foreign Office updated its travel advice for the African country, warning people not to travel to Kano.
On its website, the FCO said: "We advise against all travel to Kano whilst the curfew remains in force and for those in Kano to remain vigilant and to exercise caution.
"DFID (Department for International Development) and British Council have limited their operations in Kano whilst the curfew is in place."
It also urged British nationals in Nigeria to comply with all curfews.
Mr Hague said: "The nature of these attacks has sickened people around the world and I send my deepest condolences and sympathies to the families of those killed and to those injured.
"There is no place in today's world for such barbaric acts and I condemn in the strongest possible terms those who carried them out.
"These events underline the importance of the international community standing together in the face of terrorism in all its forms."
Friday's attacks hit police stations, immigration offices and the local headquarters of Nigeria's secret police in Kano.
One hospital official said at least 143 people were killed in the attack, but the death toll could rise because more bodies may be held at other clinics and hospitals across the city, which has a population of more than 9 million.
Nigerian president Goodluck Jonathan said Boko Haram would "face the full wrath of the law".
However, his government has repeatedly been unable to stop attacks by the group.