The British High Commission says the high demand for standard UK visitor visas has been responsible for the delay in processing.
In a statement addressed to Nigerians on Friday, the commission asked intending clients not to attend the visa application service until an invitation had been received.
It, however, said extremely compelling circumstances may be considered for expediting specific cases.
“Due to extremely high demand, standard UK visitor visas are taking significantly longer than usual to be processed,” the commission said.
“We are unable to give individual updates on applications. You will be contacted by TLS when your passport is ready for collection. Please do not attend the VAS until you have been invited to do so.
“Where there are extremely compassionate or compelling circumstances (for example, a medical emergency) we may consider expediting specific cases. However, the bar for this is high and will be assessed on a case-by-case basis.
“If your request is exceptionally urgent, you can contact UK Visas and Immigration for help. Please note that this is chargeable service for overseas customers.
“We sincerely apologise for the inconvenience to all affected customers and recognise that facing delays is really difficult for our customers.
“This is an outcome of an extraordinary travel situation we are experiencing during the pandemic.”