(Reuters) - There will be no makeup ACT college-entrance exam held in South Korea and Hong Kong, which is used to gain entry to U.S. universities, after the weekend cancellation of the tests due to leaked test material, its administrator said on Wednesday.

South Korea has become notorious for test cheating rings, while in China the U.S. College Board’s practice of recycling SAT university entrance test forms has been exploited and students given past exams and test questions in advance.

The ACT surpassed the SAT, administered by the College Board, in the United States as the most widely taken college entrance test in 2012, although it trails the SAT outside America.

As more foreign students seek entry into American universities, overseas demand for taking the ACT and its rival SAT exam is rising.

The South Korea and Hong Kong cancellations will affect about 5,500 students who were scheduled to take the test at 56 different test centers, says the Iowa-based ACT Inc.

The cancellations, just hours before students were to take the exam after discovery of a leak of test materials, marked the first known case of cancellation for an entire country, according to a ACT spokesman.

"We looked at a number of different options to accommodate the students who were, through no fault of their own, impacted by the compromised test," ACT vice president for strategic growth markets Bryan Maach said in a statement.

"Unfortunately, due to the nature of the cancellation and the ongoing investigation, ACT is unable to offer a retest opportunity before the next scheduled administration in September," Maach said.

ACT has said previously that it had received "credible evidence" that test materials had been compromised but declined to explain how the test had leaked or where.

The ACT will issue refunds for the canceled test and encouraged people to register for the September test, it said in the statement.

(Writing by Jack Kim; Editing by Michael Perry)