- 5 updates
The Fifa statement follows the killing of 13 people as they watched the Brazil v Mexico World Cup match in Damaturu, Nigeria:
A spokesman for the Nigerian World Cup squad says it is more determined than ever to qualify for the next round, after a bomb killed at least 13 Nigerians who were watching a match.
Team official Emmanuel Attah said the whole team had been deeply saddened by the killings:
Children were among the 13 people killed by a bomb blast in northern Nigeria.
More than 20 other people are in hospital; most of their injuries are serious, and include loss of limbs.
This video shows both the hospital and bombsite in Damaturu:
No one has yet claimed responsibility for the blast, though Damaturu and the surrounding Yobe state are at the heart of a five-year insurgency by Islamist militant group Boko Haram.
They have stated that watching football is "unIslamic".
Those killed were watching the Brazil vs Mexico World Cup match; the Nigerian government is advising people to avoid gathering in public to watch the matches, concerned about potential attacks.
For many Nigerians, public televisions are their only means of watching the World Cup.
At least 13 people were killed when an explosion in northern Nigeria ripped through a venue screening World Cup football, according to a Reuters reporter in the area.
The reporter said he had also counted 20 people who had been severely injured in what police have reportedly called "an attack".
The blast happened in the town of Damaturu in the northern Yobe province.
Some eyewitnesses said the attack was the work of suicide bomber, while others said they saw an attacker drop a device in front of the venue before running away.
A number of pick-up trucks carrying bodies arrived at a hospital in northeast Nigeria, a hospital source said after an explosion ripped through a venue in the town of Damaturu where fans had gathered to watch a World Cup match.
It was not immediately clear how many people had been injured or if anyone had been killed. A police official confirmed that there had been an "attack," but he declined togive further details.