Former Labour justice secretary Jack Straw has written to the Electoral Commission to ask them to investigate whether the Conservative Party broke laws banning foreign donations.
The Sunday Times secretly filmed the Conservative Party co-treasurer Peter Cruddas promising access and influence over policy to people who believed to be wealthy donors.
The undercover reporter also employed a lobbyist, Sarah Southern, to help them communicate with Cruddas.
Southern appeared to suggest that the Conservative Party would be prepared to overlook the fact that the donations would come from a foreign source.
Speaking on BBC Radio 4's Today programme on Tuesday morning, Straw said the law was "very clear" that only donations which come from individuals who are on the UK electoral roll, or from companies which are registered in the United Kingdom and trade in the United Kingdom, are allowed to make donations.
"It can include people who are on the electoral roll but, as you can be for 15 years living abroad, also includes some EU registered companies," he said.
"But the principle is very clear and in addition to this, new laws which I introduced in 2009 ensure that you can't use front organisations as, to discuss the original source of the donation, which the Conservative party were doing up to then."
Straw was reminded that no donation had actually been made to the party as the undercover reporters, but he said this did not matter.
"The criminal law has long been able to deal with people who make attempts or incite or solicit offences as well as the actual offence," he replied.