Scottish Water faces legal action over water contamination in North Lanarkshire last month which resulted in the closure of nine schools and affected thousands of homes for one week.

The threat of legal action comes from Patrick McGuire, partner at Thompsons Solicitors, who claims that the water company committed an offence under the Scotland Water Act.

McGuire told the Motherwell Times: “The act of parliament that governs the conduct of Scottish Water is quite clear. They have a statutory duty to supply the public with clean and healthy water.

“If they do not, as is the case here, then they can be held liable. My team of lawyers who are very experienced in large scale law suits are very confident residents have a strong claim for compensation and we’re already starting to take calls from worried residents.”

Scottish Water said the contamination of the water supply on 18 June resulted in the water containing an oily based substance with a strong odour.

The Scottish government has vowed to take “any necessary action” following an investigation by the drinking water quality regulator.

Responding to a question in the Scottish Parliament, Scottish minister for transport and the islands Dereck Mackay said: “Intensive work to establish the cause of the contamination continues,” he said.

He added that “all necessary action will be taken and that all relevant powers are ready to be used, should they be required.”

Scottish Water last week lifted restrictions on usage for the 6,000 properties affected and is currently carrying out an investigation and preparing a report for the Drinking Water Regulator.

A spokesman said: “It is essential that we fully understand all possible causes of the issue with the water supply.

“The investigation is being carried out comprehensively and thoroughly, before a full and detailed report on all aspects of the incident is submitted to the Drinking Water Quality Regulator.

“We are also continuing to monitor the network to ensure that drinking water supplied to our customers continues to be of the normal high quality.”