Economy Secretary Keith Brown has apologised for his role in the collapse of a possible £10 billion agreement with two Chinese companies.

The Liberal Democrats called for Mr Brown to be "censured" and apologise a year on from the signing of the memorandum of understanding (MoU) between the Scottish Government and two state-backed Chinese firms.

Mr Brown said he was "sorry", adding that the government should have known about the human rights concerns before the MoU was signed and pledged that due diligence would be carried out in the future.

SinoFortone and China Railway No3 Engineering Group (CR3) signed the MoU with First Minister Nicola Sturgeon last March but withdrew in an email to the government in August.

The deal had come under intense scrutiny from opposition parties, who accused the government of secrecy over the agreement, which only became public knowledge when it was revealed by newspapers.

It also emerged CR3's parent firm has been singled out by Amnesty International for human-rights abuses in the Democratic Republic of Congo and faced allegations of ''gross corruption'' by the Norwegian Oil Fund.

In a Liberal Democrat parliamentary debate, Mr Brown said: "I take full responsibility for the handling of this MoU and I am sorry for the issues that have arisen from it.

"I can assure Parliament that we have and will learn lessons from the experience of the MoU. We will consider human rights issues in our engagement with overseas businesses and we will only sign investment agreements where appropriate due diligence, including on human rights records of companies involved, has been undertaken."

He said the information on human rights concerns "should have been known" before the MoU was signed.

He added: "Given the concerns that have been raised I would want to assure parliament that no financial commitment was made at any point behalf of the Scottish Government and that none has been made since the signing of the MoU.

"Similarly, there have been no legal or contractual agreements with either of the companies named in the MoU and finally we've had no engagement with either company since September 2016."

Scottish Liberal Democrat leader Willie Rennie said: "Scottish Ministers were naive to lend any credibility to this enterprise. It shows how careless the First Minister was to put pen to paper on a deal with Chinese companies she knew absolutely nothing about.

"The reputation of Scotland on human rights has been tarnished by of this shambles. The prospect of investment from sound Chinese and other sources has been diminished."

MSPs voted against censuring Mr Brown after he apologised in the chamber.

Green co-convener and economy spokesman Patrick Harvie said: "This debate raised serious issues about just how compatible human rights is with trade. Human rights cannot be an afterthought.

"In dealings with countries such as China, Saudi Arabia - and perhaps increasingly in the future the US - issues of human rights and ethical business must be central to the discussion. The government is due criticism for failing to do that.

"Others seemed more interested in trying to claim a ministerial scalp than addressing the issue of human rights. Today I pressed for an apology from Keith Brown and one was given, showing he has understood the strength of feeling on this issue.

"I have disagreed with Keith Brown on a range of issues and no doubt I'll continue to do so. However, when an apology is given in good faith, I think Parliament should accept it and move on, ensuring that the mistakes made are never repeated."