Rio de Janeiro must keep up the pace of delivery if it is to complete venues before scheduled Olympic test events as it enters "the most intense period of preparations", the International Olympic Committee (IOC) said on 25 February.

With just under a year and half to go before the Summer Olympic Games in 2016, certain venues are cutting it very close, Nawal El Moutawakel, IOC Coordination Commission Chairperson, said during a visit to check on progress.

Rio is holding 21 test events, the majority of which are scheduled for the second half of this year.

The equestrian cross country is due to take place in August and the golf in November. The track cycling is scheduled for March 2016.

"Rio is entering the most intense period of preparations. A period where Rio must reach a new level of detail," she added.

In addition to the sports installations, the IOC also said Rio must focus on transportation projects and the construction of hotels.

Infrastructure projects including new roadways, tunnels, subways and mass transit systems were a major part of Rio's bid.

Some of those projects, including the underground Metro System's Line 4, have met delays.

The government has also hinted that it may not reach its goal of reducing sewage in the bay where Olympic sailing events will take place during the Games.

IOC sports director Christophe Dubi said, despite signs, the goal will not be met on time for sailors to hit the water, the 80% mark remains the target.

"We're still aiming towards this goal. And I think everybody is aiming towards this goal including the government entities that are involved. So we cannot judge until the finish line. We are like athletes in this. We are pushing towards the finish line and we should respect that. Every effort is being made at that point in time and 80% remains the commitment," he said.

The clean-up of Guanabara Bay was a key part of Rio's bid and has long been a goal of various local governments.

Hundreds of millions of dollars have already been spent, but the waters remain polluted.

Olympic sailors, who have visited the city for test events, complained of floating sofas and animal carcasses in the water, described as a "sewer".

Biologists last year said rivers leading into the bay contained an antibiotic-resistant bacteria that can cause urinary, gastrointestinal and pulmonary infections.