The canine companions of airport security staff in Manchester are quick to spot sausages and cheese in passengers' luggage but are failing to sniff out class A drugs, a report has found.

Inspectors said sniffer dogs at Manchester airport have failed to find any drugs or illegally smuggled cash. The report also found there were major faults with immigration controls, which allowed scores of passengers into the UK without the correct border checks.

The dogs failed to spot a single person carrying heroin or cocaine over the border during a six-month period studied by the independent chief inspector of borders and immigration. But one dog, trained to detect illegal animal products, often found “small amounts of cheese or sausages” carried by holidaymakers, the report said.

Inspectors said that although heroin and cocaine were assessed as “very high priority” for the search team, no class A drugs had been found by the dogs between November 2014 and June 2015.

The review assessed airport border checks by 286 staff, and the Home Office, which oversees the checks, said improvements must be made.

The airport, the UK's third largest, has six detector dogs and new kennels, which cost ￡1.25m. One dog made “accurate detections” – but most were of cheese or sausages, which the report said was a poor return on the annual cost of running the canine team.

Over the period, the dogs helped seize more than 46,000 cigarettes, 60kg of tobacco, 181kg of illegal meat, and ￡28,000 in cash. The dogs successfully detected illegal drugs on three occasions, finding small amounts of class B substances. They also found tablets of human growth hormone, Viagra and Bromazepam.

Other elements of border checks were also reviewed, with the report finding that:

- A significant number of Border Force staff at the airport were not fully trained in immigration work, leading to delays and inefficiencies in the processing of passengers.

- Some staff were called upon to supervise immigration functions at a terminal for a shift without the relevant immigration knowledge or training.

- There was a “control breach” in April 2015 when 150 passengers from a delayed Ryanair flight were “misdirected through an unmanned immigration control”, meaning they were able to leave the airport without their passports being checked. Managers “acted decisively” to deal with the breach.

A number of passenger entries were also questioned in the report. These included:

- An American passenger on a two-month visit with just ￡37 to his name who had just returned from Egypt on an Islamic studies course.

- A 12-year-old Japanese boy who arrived alone to be picked up by a “dishevelled” man who admitted no schooling arrangements had been made and interacted badly with the boy. When social services weren't available he was granted entry anyway.

- A Chinese national with a visa declared an amount of money for “tourism and shopping” which was well above his annual income. He was allowed in for six months, which should not have been permitted without a luggage check or interview, according to the inspector.

- An American professional poker player who wanted to meet a woman he had met on Facebook. Declaring himself a medical marijuana user, he was granted temporary admission to visit the woman until his flight five days later. The inspector said there should have been more checks because two children lived at the woman's home and he should have been told medical marijuana was illegal in the UK.

A Manchester airport spokesman said staff “work extremely closely” with the Border Force and “support their work to address the issues raised in this report”.