The Ministry of Education was forced to intervene in almost 50 at-risk schools last year, more than four times as many as in 2007.

Under the Education Act 1989, the ministry can intervene where it believes there is risk to the operation of the school or the welfare or educational performance of the students.

Its figures for 2009 showed specialist help was required in to pull schools out of trouble in 47 cases.

That was an increase of more than 50 per cent from 2008, when there were 32 interventions, and more than 400 per cent from 2007, when there were 11.

Ministry of Education Auckland regional manager Bruce Adin said the number of interventions fluctuated from year to year, but a consistent rise would be concerning.

"We don't like seeing an increase like that.

"If it continues to track up like that I'd be concerned, but you can have change like that," he said.

He said most cases of intervention used Education Review Office (ERO) reports as a starting point.

"We consider the ERO recommendation and then combine with other information they have about the school.

"From that we form a formal intervention report and make a recommendation to the minister."

Mr Adin said many factors could lead to intervention, from problems with the board of trustees to fund mismanagement or student trouble.

Although all cases went through the same process, each was a unique operation, Mr Adin said.

Intervention ranged from the dissolution of a school's board and appointment of a commissioner, to bringing in a limited statutory manager or specialist adviser.

Every case is reviewed at least every 12 months and adjusted according to its success.

"Most of them have positive outcomes," Mr Adin said.

The main aim of an intervention was to stop intervention being necessary, he said.

"The limited services manager is there to do themselves out of a job."

Mr Adin said with about 6000 schools in New Zealand, interventions were rare but "one's one too many".

Secondary Principals Association of New Zealand Peter Gall said intervention was the ultimate step that the ministry had.

"I think it's a very important thing to have in place but you'd want to make sure it's used appropriately.

"I think it's necessary to have that backstop there but you wouldn't want it to be overused," Mr Gall said.

ERO chief review officer Dr Graham Stoop said only a "very small amount" of reviews resulted in interventions.

"It would have to be quite serious for us to dissolve a board and appoint a commissioner," he said.

Some examples of recent interventions involved allegations of financial troubles and mismanagement by Hamilton's Fraser High School and staff reporting feeling unsafe at Northland's Whangaroa College.

A limited statutory manager was appointed to Fraser High School in early November following a report by accountancy firm Pricewaterhouse Coopers, which claimed former principal Martin Elliott illegally accepted extra salary and falsified invoices after using school money on personal properties.

This was despite positive reviews in the school's 2007 ERO report.

Whangaroa College was appointed a limited statutory manager in November following a special ERO review in September.

According to the ERO report, "more than half the staff feel unsafe in the school because of student or staff behaviour and inconsistencies in the implementation of school systems, policies and procedures".

"The board is not providing a safe emotional and physical environment for staff and students," the report said.

There are six ways the ministry can intervene in schools deemed at risk.

* A school's board of trustees to provide specified information Education Act (section 78J) or enlist specialist help from particular people or organisations (section 78K).

* A board of trustees can be asked to prepare and implement an action plan to address specific issues (section 78L).

* The Minister of Education can remove power from the board of trustees and appoint a limited statutory manager to complete the board's responsibilities which have been taken from them. (section 78M).

* The minister can also dissolve a board of trustees and direct the Secretary of Education to appoint a commissioner to replace the board - section 78N(1), (2) and (3).

Interventions in 2009

Auckland Point School 78K
17-Feb-09

Barrytown School 78N(1)
14-Aug-09

Birdwood School 78k
27-Feb-09

Broomfield School 78K
22-Jul-09

Fairfield College 78N(3)
23-Feb-09

Hamilton's Fraser High School 78M
9-Jun-09

Hammersley Park School 78N(1)
16-Oct-09

Hokitika Primary School 78M
20-Aug-09

Howick College 78K
12-Jun-09

Kaikorai Valley College 78M
7-Aug-09

Kaingaroa Forest 78M
24-Sep-09

Kawerau North School 78M
11-Sep-09

Mangakahia Area School 78K
2-Oct-09

Manukorihi Intermediate School 78N(3)
1-May-09

Marfell School 78M
9-Oct-09

Marlborough Boys' College 78M
28-Mar-09

Muriwai School 78K
30-Jan-09

Orini Combined School 78K
3-Apr-09

Otago Boys High 78L
16-Jul-09

Otakiri School 78M
21-Mar-09

Otepopo School 78N(1)
13-Mar-09

Pukekohe High School 78K
24-Jul-09

Raphael House Rudolph Steiner School 78M
5-Jun-09

Raphael House Rudolph Steiner School 78K
3-Mar-09

Richmond School 78N(3)
17-Apr-09

Riverhills School 78M
6-Aug-09

Robertson Road School 78M
8-May-09

Rosebank School 78M
9-Jun-09

Selwyn College 78N(1)
21-Jan-09

Sherwood School 78M
1-May-09

Sir Edmund Hillary Collegiate 78N(1)
30-Jan-09

St Joseph's School (Hastings)78M
21-Aug-09

St Matthew's School 78K
9-Sep-09

St Peter Chanel School 78K
15-Jul-09

Stratford High School 78M
9-Jun-09

Taumarunui Primary School 78K
13-Mar-09

Taupiri School 78M
21-Mar-09

Te Kainga Whaiora Children's Health Camp 78N(1)
13-Feb-09

Te Kura Kaupapa Maori o Hoani Waititi 78M
23-Oct-09

Te Kura Kaupapa Maori o Hoani Waititi 78K
23-Oct-09

Te Kura Kaupapa Maori o Waiuku 78K
2-Jul-09

Te Kura o Otangarei 78M
7-Aug-09

Te Puke High School 78K
14-Apr-09

Tokoroa Central School 78M
20-Mar-09

Wairakei School 78M
16-Jan-09

Whangaroa College 78M
9-Oct-09

Whangaruru School 78M
24-Jul-09