Salmon farms in Scotland could face tighter regulations.

The environmental watchdog Sepa found that the existing approach to salmon farming does not do enough to protect marine life, raising particular concerns about the chemical treatments for parasitic sea lice.

The tiny lice attach themselves to salmon and feed on them, killing or rendering them inedible.

Sepa tested waters for specific chemicals that were used to treat the sea lice until 2013, and found them to have a greater and longer-lasting impact on the environment than previously thought.

The proposed new restrictions will limit the future use of the chemicals and could mean some farms will have to relocate to deeper waters with stronger tides.

Terry A'Hearn, chief executive of Sepa, said: "Our job is to make sure environmental standards protect the marine environment for the people of Scotland and we make sure the industry meets those.

"That's unequivocally our focus.

"Across the last 16 months we've done more science, more analysis and more listening than ever before.

"Whilst we're seeing innovation in the sector, we've concluded that Scottish salmon farm medicine is significantly impacting local marine environments which increases the weight of scientific evidence that the existing approaches do not adequately protect marine life.

"This is why we're announcing firm, evidence-based proposals for a revised regime that will strengthen the regulation of the sector."

Sepa is launching a seven-week consultation on the proposals and will host a series of nine events across Scotland during November and December.

Julie Hesketh-Laird, chief executive of the Scottish Salmon Producers Organisation, said: "This is a rigorous report setting out the modern regulation the industry needs enabling it to grow sustainably over the long term.

"It is the culmination of years of collaborative work between the Scottish salmon farmers and Sepa to develop a new framework for the gradual and careful expansion of the Scottish salmon sector.

"We share Sepa's vision of an innovative, sustainable salmon industry underpinned by clear and accurate regulation.

"This report will remove many of the barriers preventing the development of more modern facilities further from the shore and we look forward to Sepa's support as the industry makes this change. "