There were "serious failings" in the anti-doping operation used at the Rio 2016 Olympic Games, a report by the World Anti-Doping Agency (WADA) has said.

The report accuses the department responsible of a "lack of coordination", with "budget and operational cutbacks" contribing to an almost "unmanageable" strain on drug testing at some venues and at Athletes Village.

Up to half of all tests due to be carried out at the Village were cancelled because competitors simply could not be found, it revealed.

Transport arrangements for doping officials to get between venues were often "inadequate, or even non-existant", it said, while computers and printers sometimes did not work.

In total, almost 500 fewer anti-doping tests were carried out than had been planned - 4,882 compared to the 5,380 scheduled.

And of the 450 Athlete Biological Passport tests due to be done, only 47 were carried out.

The report praised the Games' "dedicated" staff on the ground, saying were it not for their hard work, "the Games anti-doping programme would have almost certainly collapsed".

"Due to their initiative, tenacity and professionalism in the face of great difficulties, the many problems identified... were patched over and sample collection was conducted in a manner that ensured the identity and integrity of the samples," it said.

In particular, the doping control station managers "received no on-site training... no venue-specific information and no sport-specific guidelines" - but carried out the planned tests as best they could.

But despite its criticisms, the WADA report praised the Brazilian Doping Control Laboratory, which had had its accreditation suspended ahead of the Games for failing to comply with international standards.

The report said the laboratory was "superbly equipped, operated very securely and generally very efficiently, and now represents an outstanding legacy from the Games for the anti-doping movement in South America".