Croatia police Wednesday arrested a former minister and three other people suspected of fraud related to the allocation of EU funds, the European Union's prosecutors and local media said.

The four were arrested for suspected fraud over "public procurement procedures for purchasing an information system", the European Public Prosecutor's Office (EPPO) said in a statement.

The alleged offences were committed at the ministry of regional development and EU funds, as well as at the Central Finance and Contracting Agency handling the bloc's projects, it added.

The EPPO said it was conducting "urgent evidence-collecting activities" along with Croatia's anti-graft police.

State-run HINA news agency said the arrests were linked to a software development project worth around €2 million that the ministry in 2018 allocated to a local company.

Local media said those arrested included Gabrijela Zalac, who headed the regional development ministry from 2016 to mid-2019, and Tomislav Petric, the current head of the Central Finance and Contracting Agency.

Zalac is a member of the ruling conservative HDZ party.

She served in Prime Minister Andrej Plenkovic's former government from 2016 to mid-2019, before being sacked in a major cabinet reshuffle.

Asked to comment on her arrest, the premier said he was surprised but stressed that "independent" judicial bodies were "doing their job".

"Our job is to fight corruption," he told reporters.

The battle against graft was key for Croatia's successful bid to join the European Union in 2013.

The Luxembourg-based EPPO started work in June with a focus on tackling suspected fraud involving the bloc's budget, and has delegated prosecutors in member states.