Monrovia: All of Liberia's 25,000 candidates who took this year's university entrance exam have failed - but the students say they suspect foul play.

None of the candidates scored more than 50 per cent, according to officials on Tuesday at the University of Liberia in the capital, Monrovia.

To be admitted, a student needs to secure a score of at least 70 per cent.

"For me, the whole thing is laughable, that 25,000 people would take an exam and not even one person would pass," Lee Walkie, a senior student at the uni, said.

President Ellen Johnson Sirleaf said earlier this year the West African country's education system was "in a mess".