Labour has insisted it complies with the UK's visa rules over the activities of US political campaign guru Arnie Graf following Tory questions about his relationship with Ed Miliband's party.
Mr Graf, a veteran community organiser who has provided advice on grassroots tactics for Labour, has a business visa allowing him into the UK but he cannot be paid a salary for his work.
Labour has said it reimburses Mr Graf for lost earnings and expenses on his visits to the UK but said he was not paid a wage and did not require a work permit.
The party stressed that Mr Graf was not employed by Labour and did not live in the UK, but only visited "a couple of times a year".
A Labour Party spokesman said: "Arnie Graf has a visa which allows him to enter the UK for permitted business activities. These activities have been fully disclosed to the UK immigration authorities when obtaining the visa .
"He is not employed by the Labour Party but advises us on campaigns and we reimburse him for lost earnings and expenses."
Tory MP Priti Patel called for Labour to clarify the party's financial relationship with Mr Graf.
She told The Sun: "Labour must declare their full financial relationship with Mr Graf so that voters are left in no doubt that he is not an illegal immigrant.
"Business visas are about those who come to Britain and contribute on economic grounds. If there has been any misrepresentation, the Home Office should look into it urgently."