Samaritans leaders today voiced concern over a drop in volunteer numbers as the volume of calls increases.

The charity is now looking to recruit hundreds of new volunteers to cope with the growing workload.

An appeal came as public health minister Shona Robison visited the charity's branch in Dundee this morning to lend support for its work.

Frances Simpson, the organisation's Scottish development officer, said today that calls to the service hit 6000 in 2006 - up 5% on the previous year.

At the same time volunteer numbers dropped from 961 in 2005 to 930 last year.

She said: "It might not sound dramatic, but it's worrying. It's a slow, steady decline and it equates to about 100 hours a week in volunteering.

"The impact on the branches is considerable.

"That's why we need to start reversing that because it impacts on things like publicity, training and fundraising which the volunteers also do."

The Samaritans now want to increase its current compliment of just over 900 volunteers to 1200 over the next couple of years.

The stresses of work, relationships and debt are believed to be among the reasons behind the rise in calls.

Increasing awareness campaigns have also brought down the barriers to many Scots reaching for the phone and seeking help in such situations.

Ms Robison's visit was among more than 200 events going on today as part of the charity's 24:7 campaign throughout the UK to raise awareness of its round the clock support service and raise funds.

"We're very pleased that the minister was able to get along," said Ms Simpson.

"She met about half-a-dozen volunteers and offered her support for the work that we do."