Nicola Sturgeon has said no deals will be done with a Chinese consortium if legitimate concerns about the firms involved are uncovered.
The SNP leader signed a memorandum of understanding potentially worth £10bn last month.
The Herald newspaper said China Railway Group Limited (CRG) and subsidiaries were named in an Amnesty International report on human rights abuses.
Opposition parties have urged the SNP leader to reconsider the agreement.
In March, Ms Sturgeon signed a “memorandum of understanding” between the Scottish government and SinoFortone and China Railway No 3 Engineering Group, a wholly-owned subsidiary of CRG.
It has previously emerged that CRG has been hit by corruption allegations in its homeland which resulted in Norway’s oil fund blacklisting the firm.
On Saturday, the Herald reported claims from a 2013 report by Amnesty International on mining and human rights in the Katanga region of the Democratic Republic of Congo.
The newspaper said researchers for the charity were told that 300 households were forcibly evicted in 2011 when the Congo International Mining Corporation (CIMCO), a subsidiary of CRG, was given the rights to a site where they had been living since 2007.
The charity said it had received no response from CIMCO in relation to the allegations.
‘Options for investment’
Asked about whether the allegations in Herald’s story would impact on the agreement with the Chinese consortium, the SNP leader said: “There is no deal done.
“There is a memorandum of understanding to explore potential options for investment in Scotland.
“If there are any particular and specific deals that come forward then the Scottish Parliament would scrutinise those, the Scottish government would do proper due diligence, and if there were any concerns that said these were deals we should not do then we wouldn’t do them.
“With every utterance they make about this, seemingly looking as if they are against exploring investment into Scotland, then I think the opposition parties raise more questions about themselves rather than about the Scottish government.”
Scottish Liberal Democrat leader Willie Rennie called for the agreement to be torn up.
He said: “The SNP have talked tough on tax avoidance and fair employment but they have rejected my calls to end government grants to companies who avoid tax or fail to pay the national living wage.
“Worse, they seem happy to get into bed with companies who have been blacklisted by the Norwegian oil fund and criticised by Amnesty International over their human rights record.
“This is not simply about Nicola Sturgeon’s gross error of judgement. This SNP deal is dragging Scotland’s reputation through the mud. The first minister must shred this deal.”
‘Need questioned answered’
Speaking on the election campaign trail in Edinburgh, Scottish Labour leader Kezia Dugdale said: “There’s a complete lack of openness and transparency about this.
“We don’t know what this means for Scottish jobs, for Scottish businesses and we don’t know the details of some of the dark activities of the companies involved.
“I would urge the Scottish government, as I did before, to show us the detail of this deal.”
Scottish Conservative leader Ruth Davidson said: “The more we find out about the Chinese companies Nicola Sturgeon has been making memorandums of understanding with the more we realise why she wanted to keep it secret before this election campaign.
“It’s not good enough. We need all of the questions answered as to why a company like this – that’s not just been pulled from the Norwegian oil fund because of allegations of corruption, but has now been blacklisted by Amnesty International – are signing bits of paper in Bute House.”
Away from the issue of the Chinese investment agreement, on the final weekend of campaigning ahead of the Holyrood election the party leaders were out and about making a push for votes.
Scottish Labour leader Ms Dugdale launched a new billboard poster in Edinburgh pledging to “stop the cuts”. She claimed analysis suggested every Scot could benefit from £600 higher public spending under her party’s tax plans.
She said: “The new powers of the Scottish Parliament mean there is a clear choice in this election.
“We can vote to carry on the cuts with the SNP and the Tories or stop the cuts with Scottish Labour.”
Ruth Davidson, Conservatives
The Scottish Conservatives said they would be holding a total of 130 street stalls across the country on Saturday.
Speaking to voters at a stall in Edinburgh, leader Ms Davidson said: “The scope of our campaigning events today show the level of our ambition at this election.
“We want to represent all of Scotland and become Scotland’s main opposition.”
Nicola Sturgeon, SNP
The SNP said it would have 50,000 activists out across Scotland over the weekend and aimed to reach 2.4m households in 48 hours.
Speaking to supporters in Stirling, party leader Ms Sturgeon said: “This week’s election is about who becomes first minister, who forms the government of Scotland and who will always stand up for Scotland.
“Voters have the chance, by using both votes for the SNP on Thursday, to elect me as first minister for the first time, and to ensure Scotland continues to move forwards.”
Willie Rennie, Liberal Democrats
Liberal Democrat leader Mr Rennie was in Dundee where he was turning his attention to seats where his party has never won before.
He said: “Voters have less than a week to ensure that the next five years are about schools, health, the environment and civil liberties.
“You only get that with the Liberal Democrats and that is why we will grow at this election.”