Britain has issued a travel advisory urging people not to visit Afghanistan.

"The Foreign, Commonwealth & Development Office (FCDO) advises against all travel to Afghanistan," the advisory said.

"You should not travel to Afghanistan," the travel advisory mentioned.

The British government said terrorists are very likely to try to carry out attacks in Afghanistan.

"There is a heightened threat of terrorist attacks in or around religious sites and during religious events and celebrations, such as the month of Ramadan," the advisory said.

"The security situation in Afghanistan is volatile. There is an ongoing and high threat of terrorist attacks throughout Afghanistan, including around airports," the advisory further said.

The advisory warned there is a significant risk of detention of British nationals.

"The British Government may not be notified about such detentions  and there are considerable challenges in securing consular contact or access. You  may not be able to contact your next of kin and detention may be lengthy without clarity being given to your charge," the advisory said.

The British government warned that the Kabul International Airport does not meet international aviation safety standards.