Mental health charity Lifeline has announced its Crisis Text helpline will expand to operating all hours of the week amid high demand for its services.

The Crisis Text service was introduced in 2019 and since then has provided support for vulnerable people in hard-to-reach groups, including people experiencing domestic violence.

Lifeline CEO Colin Seery says the service has helped the charity provide support to new groups of people, including those for whom "accessing support through digital communication is the only safe or viable option".

"The service is unique in that it allows for genuine privacy during contact, so it is well suited to support cohorts at heightened vulnerability such as help seekers experiencing domestic and family violence or those living with a disability," Mr Seery says.

A 2019 evaluation of the text service by the Australia Health Services Research Institute showed 42 per cent of people specifically looking for the text and chat support, noting they would not use an alternate service.

Of 1000 people who provided demographic data, 80 per cent of them were women, with the median age of those seeking help 24.

Federal Health Minister Greg Hunt says more people have been seeking support throughout the pandemic but the text service was particularly valuable for some groups.

"The expansion of the text service is backed by data showing that it is the preferred channel for high risk members of the community including young people, those experiencing family and domestic violence, and Aboriginal and Torres Strait Islander people," Mr Hunt says.

Demand for Lifeline's services has increased throughout the pandemic, with the charity fielding more than 1.1 million calls last year, including 3641 calls on its single busiest day in September.

Those using the text service have also increased, with volumes there rising by 31 per cent between October and January.

The federal government has awarded a $1.5 million grant to Lifeline to expand, on top of $2.5 million of COVID-19 response funding that has previously supported the service.

The charity also receives $1.5 million a year from the NSW government to support Lifeline Crisis Text, as well as support from the private sector including Woolworths, RACV, nib Group, AGL, and the charitable arm of Domino's Pizza.

NSW Mental Health, Regional Health and Women Minister Bronnie Taylor says it's important people can quickly access mental health support, "especially for those in difficult living environments".

The text service is "uniquely placed to deliver that immediate help," Ms Taylor says.

Lifeline is currently training new volunteers to help run the expanding service, with up to eight crisis support staff per shift offering psychological support.