More than 700 Tusla employees have left the agency over the last 21 months.

According to details released to Newstalk under the Freedom of Information Act, 347 staff left the Child and Family Agency last year.

Factors such as lack of job satisfaction, promotional opportunities and unsuitable hours were some of the reasons for their departure.

The data shows the turnover rate among social workers is highest across the agency at 8%.

Kathleen Funchion is Sinn Féin's Spokesperson on Children.

She said more resources are needed to deal with recruitment and retention.

"I think what we need to do is we need to look at how we can reduce the burden on staff, how staff can be supported, how they can be supported to stay in those roles and those positions," she said.

"Every time somebody leaves, and somebody new comes in, you have to go through all that process again [with] somebody settling in, training in.

"We are seeing maybe some people leave for the private sector where the caseload maybe a lot more manageable.

"You have to remember as well - particularly in the area of social work - if you've gone into that type of work, you really want to make a difference and you really want to help people.

"If you're getting to the stage where you've got so many cases that you just don't even know where to start with it, it's very, very frustrating".

'Not unique to the Irish context'

A spokesperson for Tusla said the agency "continues to face challenges in relation to the recruitment and retention of staff".

"However, it should be noted that these issues are not unique to the Irish context and are a common concern, for many other European social and health care providers.

"Staff retention is a key strategic priority for the Agency and is one of the cornerstones of the new Tusla People Strategy, which outlines our focus on developing a stable workforce in the years ahead for the benefit of children and families and the best possible opportunity for Tusla to be the public sector employer of choice.

"Staff decide to leave Tusla, and other similar organisations, for a wide range of reasons and to facilitate their goals and situations.

"That said, we are aware that child protection social work is a challenging career, and, on some occasions, people decide to change direction," they added.