STATE Trustees has come under investigation for an surge last financial year in complaints from clients, many of whom are vulnerable.

The Victorian Ombudsman announced on Tuesday it had launched the investigation after complaints increased by 37 per cent in the 12 months to June 30, 2017 and remained at the same level in the most recent financial year.

But the Victorian government-owned agency, which has an office in Bendigo, countered that it had experienced an unusually low number of contacts made by clients to the ombudsman in 2016, otherwise the number had been consistent over five years.

From 213 contacts in 2014 and 208 in 2015, contacts with the ombudsman declined to 161 in 2016, rising to 216 in 2017 and 220 last year.

“Only some of these contacts resulted in an inquiry by the ombudsman to us,” a State Trustees spokesman said.

Ombudsman Deborah Glass was more specific, saying that while investigating complaints, she had identified systemic issues “that warranted a deeper examination”.

“People have complained that State Trustees did not consult them about decisions or take their wishes into account,” Ms Glass said.

“There have been complaints that State Trustees did not pay bills or other expenses in a timely way.

“Others have said communication with State Trustees is difficult.

“Many of the people who rely on State Trustees are vulnerable, and I want to ensure their rights are respected and protected.”

State Trustees has a role managing money for people who due to disability, illness or injury, are unable to do so.

The agency has more than $1 billion under management, and more than 11,000 clients.