The Calgary family of a rock climber missing on a Scottish mountain since the weekend is remaining hopeful and making a plea for witnesses to come forward, Police Scotland said in a release Thursday.

Search and rescue efforts for Rachel Slater and Tim Newton, however, have been called off for a second time due to "treacherous weather and dangerous underfoot conditions."

Slater, a U.K. citizen, lived and attended school in Calgary between 2005 and 2009.

The pair, both experienced climbers, were last seen over the weekend in the Ben Nevis area of the Scottish highlands, about 190 kilometres northwest of Glasgow.

Slater's family, who live in Calgary but have joined the Scottish search, said in a release the support they have experienced has been incredible.

"We are extremely grateful to members of the emergency services and search and rescue personnel who are searching for Rachel and Tim," the family said.

"The overwhelming response from members of the public and the climbing community has greatly assisted the search effort and we appreciate all the support and words of encouragement."

Police Scotland said the search effort was called off Thursday for a second time. It had resumed Wednesday after conditions Tuesday made it impossible to continue.

Police say further updates will be posted to their Facebook page.

Lochaber Mountain Rescue Team is also posting search and rescue efforts.

The family is hoping anyone who may have seen the couple will contact investigators.

"As a family we urge anyone who was in the Ben Nevis area last weekend and may have seen or spoken to Rachel and Tim at any time to get in touch," the family said.

Tim Newton, Rachel Slater

Rachel Slater, right, and her partner Tim Newton have been missing from the Ben Nevis mountain area of Scotland since the weekend, despite a large scale search and rescue. Slater lived in Calgary between 2005 and 2009 and her parents still do. (Police Scotland)

"We think Rachel was climbing in a turquoise jacket and purple helmet. Tim may have been wearing a red jacket, similar to the photo in circulation."