The National Crime Agency (NCA) has been criticised for failing to issue its officers with radios meaning they sometimes have to use personal mobile phones to dial 999 for back up when they are in danger.
A report by Her Majesty’s Inspectorate of Constabulary Fire and Rescue Services (HMICFRS) also found agents in the field often used their own smartphones to collect evidence, such as taking pictures of suspects.
Inspectors described the practice as unacceptable and recommended it was addressed immediately.
The NCA, which is dubbed Britain’s FBI, deals with serious and organised crime, including tackling the trade in drugs and guns, people trafficking and child sexual exploitation.
Its operations bring its officers into contact with some of the world’s most dangerous criminals, but the report found that they did not always have the same standard of equipment as local police forces.
They pointed out that in some cases, cameras and recording equipment were out of date, leading to officers using their own personal smartphones to take pictures and record footage of suspects.
Inspectors said: "The quality of equipment available to surveillance officers has not kept pace with that available to regional organised crime units or police forces.
"The NCA is dealing with the most sophisticated criminals in the UK and abroad and yet there are examples of vehicles barely used because they are equipped with out-of-date cameras and recording equipment.
"We heard of several examples of officers using their own mobile phones to capture subject images to pass to colleagues in the field. This is unacceptable and must be addressed."
The report was also damning about the use of radios by the NCA warning that they were not always issued and when they were officers did not necessarily know how to use them.
When radios are given to frontline officers it allows force control rooms to track them and see where everyone is at any one time.
However inspectors said the NCA did not have this facility and radios were not issued to officers as a matter of course.
Instead they could take radios from a pool, but often did not bother because they were unsure how to use them.
The report warned: "We found there were occasions when officers attending warrants or dealing with offenders did not have a radio or had not logged on to their radio.
"This leaves officers at risk if an emergency response is needed. We were given accounts of officers using the 999 system to get assistance in volatile situations.”
Matt Parr, Her Majesty’s Inspector of Constabulary, said: “While we found evidence of good practice, we also had concerns in some areas – including the use of personal mobile phones during covert operations, and officers not always having access to radios – which could mean they are at risk in volatile situations. The NCA has told us that it has now taken steps to rectify these issues.”