Tehy, the Union of Health and Social Care Professionals, has filed a criminal complaint with police over wages not paid to union members by the City of Helsinki.

In a press release, the union stated that the payroll problems have been going on for months and have been affecting several thousand workers in the capital region. The paying of overtime and bonuses, which are a large part of total wages in the social and healthcare services sectors, have been a particular issue.

"Several hundred employees have not received their full salary for several pay periods," the union's Head of Legal Services Kari Tiainen said.

The City of Helsinki has been dealing with technical problems in its payroll system since April, with the city's financial management department reporting some 7,000 unread messages regarding payroll issues by the middle of last month.

This has led to some unpaid workers resorting to taking out high-interest payday loans and second-hand trading to cover daily expenses

Tehy: Who is responsible?

In its criminal report, Tehy has asked police to investigate who is ultimately responsible for the payroll problems. The union noted that that the overall responsibility likely lies with the City Office and City Manager Sami Sarvilinna.

The city has stated that the issues are being caused by IT problems, as employee data has not transferred correctly from an old payroll system to a new database.

The City has also blamed the problems on a strike by healthcare workers during the spring.

"Workers were on strike from 3 to 9 May only. They should have been prepared much earlier for such a major change in the system," Tiainen told Tehy's inhouse newspaper.

The union has previously submitted a request to the Regional State Administrative Agency about the unpaid wages, and other unions in the sector have also taken a stand.

The City of Helsinki is the largest employer in Finland, with around 38,000 employees.

At the end of June, the City estimated that the payroll issues affected around 5 percent of its entire workforce.