The Department of Health has spent more than £2.5m advertising on Google in the past year, it has emerged.

Using the internet search engine’s pay-per-click “AdWord” service, the DH spent £2,720,457.11 between 1 February 2009 and 31 January this year, health minister Phil Hope said.

It paid for 21,939 “active search terms”, he revealed, but said setting out what had been chosen could put the DH at a “future competitive disadvantage”.

Google AdWord allows clients to select relevant search terms that will bring up an advert for their services. Clients are then charged if internet users click on the advert.

In a written Commons answer to Tory MP Nick Hurd, Mr Hope said the DH’s active terms included searches on specific campaigns and NHS Choices - the “front door” to the NHS, according to its website.

“In relation to which Google keywords have been bought for use, such information is commercially sensitive,” Mr Hope said.

“The commercially competitive nature of the cost of Google AdWord keywords means that putting specific information in the public domain on actual keywords used could put the department at a future competitive disadvantage.”

A Department of Health spokesperson said: “Our campaigns are designed to deliver better health, whether they be to help people change their behaviours to protect their long term health, to signpost people to NHS services, or to encourage healthier lifestyles.

“The campaigns are evaluated using a combination of robust techniques that help us identify exactly what works, so we know that these campaigns are saving lives.”