The Hong Kong Jockey Club is reviewing its security measures after confirming three open containers of paint were thrown over the fence and onto the back straight of the Happy Valley track during Wednesday night’s races.

The containers were found during a routine track inspection after the seventh event on the nine-race card and led to race eight jumping late.

While licensing committee secretary Steve Railton, who was chairman of stewards on the night, said the Jockey Club’s race-day coverage did not capture the perpetrators, he said security will search for any outside footage along Wong Nai Chung Road that may shed light on the incident as they continue to investigate.

“Obviously, somebody has thrown them over the fence,” Railton said. “It was between race seven and eight that it was detected and, on viewing footage of race seven, there was no evidence of it having occurred during the running of the race.

“Security will be following up thoroughly on what actually occurred and putting things in place for future race meetings to guard against anything like that happening again.”

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Railton said the containers did not land in a position where they could have affected the safety of horses or jockeys and said race eight did not jump until the track was declared safe.

“They landed towards the outside of the track and not on the racing surface, not nearer to the rail where the races are conducted,” he said, adding that paint spilled on to the track.

“The club’s track staff were very diligent and identified it promptly and it was cleaned up. With the guidance of security, there were all measures put in place to ensure that there was no potential for the safety of the horses or riders to be compromised.

“The area was completely scoured and it was ensured that there was no way that anybody could impact upon race eight.”

The eighth event jumped several minutes late and security was beefed up for the remainder of the night.

“It was decided to hold the horses behind the starting gates to ensure the start of race eight would only commence when racing stewards were satisfied that it was safe to go ahead,” the Jockey Club said in a statement.

“An additional number of security staff were deployed alongside the normal patrolling security staff to ensure no similar incident could occur.

“The club takes this very seriously and is looking into the case thoroughly and will review security measures.”

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The incident comes after a turbulent few weeks for the Jockey Club, with the Happy Valley race meeting on September 18 cancelled when Hong Kong Bet, the horse owned by polarising pro-establishment political figure Junius Ho Kwan-yiu, was entered to run but the likely presence of protesters prompted safety concerns.

It evoked memories of a potentially more sinister event at Happy Valley in 2007 when ground staff uncovered a poison dart system buried near the 1,200m starting point, with the plan seemingly to fire darts into the horses before the start of the race.