Aberdeen MP Kirsty Blackman has branded reports that Downing Street is preparing to create up to 40 new peers as a “new low for Westminster and UK democracy”.
The SNP’s spokeswoman on the House of Lords accused the Conservatives of “breathtaking cynicism”.
Her comments came after a national newspaper reported that preliminary discussions have begun over the next round of appointments, with a view to a list of recommendations being finalised as soon as July.
The suggested timing has prompted a claim that donors and supporters of the campaign for Britain to remain in the EU could be rewarded.
Mrs Blackman, who represents Aberdeen North, said: “This is a new low – even for Westminster.
“Just for agreeing with David Cameron’s policy, there may be a seat in the UK Parliament – forever, without bothering about an election or being accountable in any way.
“The House of Lords is already significantly bigger than the democratically-elected Commons and at this rate will swell to the size of the Chinese National People’s congress in Beijing.
“The appointments system is ripe for abuse and needs to go. The House of Lords is an affront to democracy.
“We need to be rid of this unaccountable, undemocratic, gilt-clad chamber.”
However, when asked about the claim during a briefing at Westminster, the prime minister’s spokeswoman said it was “pure speculation”.
Last year, the Government was defeated in the “Other Place”, as the Lords is referred to in the Commons, over its tax credit proposals.
According to the UK Parliament website, there are currently 250 Conservative peers out of a total 816.