Two top Liberal Democrat donors have been questioned in connection with an investigation into allegations of bribery at Rolls-Royce.
Sudhir Choudhrie and his son Bhanu were arrested on Wednesday as part of an investigation into allegations of bribery in Indonesia and China.
The Choudhrie family and their businesses have donated more than £1.5m to the Liberal Democrats since 2004.
The men, who have been bailed without conditions, deny the allegations.
They were arrested as part of the serious fraud office's investigation into allegations of bribery in Asia by Rolls-Royce, which makes engines for military and commercial jets and ships
The Liberal Democrats confirmed they are aware of the SFO's investigation but say that whilst it is ongoing they cannot comment.
The Choudhrie family businesses, C&C Alpha Group, C&C Business Solutions & Alpha Healthcare, have donated more than £1.3m over the last 10 years.
This included donations in 2010, the general election year, totalling £415,000, which accounted for 8.5% of all the donations the Liberal Democrats received that year.
Sudhir Choudhrie and Bhuna Choudhrie have personally given £185,000 to the party since 2004.
Sudhir Choudhrie, 65, who is originally from India, lives in London and is reported to have arrived in the UK 10 years ago.
Home Secretary Theresa May presented him with a lifetime achievement award at the Asian Business awards in March last year.
In an interview after the ceremony, he said the secret of his success was ''hard work and nothing else but hard work''.
The family's portfolio of companies include businesses that specialise in providing services for the elderly and mentally ill.
The parent company of Alpha Hospitals Ltd is Harberry Investments which is registered in the British Virgin Islands, a tax haven.