The El Clínico hospital in Malaga detected a higher than usual number of positive results for occult blood in stool samples in May's colon cancer screening programme. These would therefore be false positives and the hospital is repeating the procedure to guarantee accurate results.

The samples in question belong to 400 people, among whom there were more positive results than usual.

This technical issue has led to the erroneous notification concerning positive results to some of these people, as Málaga Hoy reported on Wednesday.

The regional ministry of health has told SUR that "laboratory workers had detected the error" and "immediately begun a review of the procedure, verifying the existence of a technical incident that could be generating false positives".

The regional ministry has informed the health districts this issue concerns and launched the review with the aim of contacting individuals and offering them a repeat faecal occult blood test.

"Everyone is called back and the test is repeated due to an anomaly in the procedure," health sources told SUR.

"The rate of positive results was higher than usual, so everything was reviewed and the workers quickly detected the error, which ultimately turned out to be due to overzealousness," they said.

The samples come from some health centres in the Costa del Sol and Guadalhorce health districts that depend on El Clínico.

Typically, for every 100 people, there are between five and eight positive cases.