In an interview to party mouthpiece 'Saamna', Thackeray said Sonia was a foreigner.
"What love will she have for this country and what is her contribution here," he asked. "You see what is going on in the country. There is controversy over the Army chief's age and the matter is in court.
Whose reputation is in jeopardy? There is no question of Sonia's reputation as she is a foreigner," he said.
On Rahul, he said, "He was born yesterday and wants to be prime minister.
Is the PM's post up for auction?" The atmosphere in the country was polluted by Congress, he said.
Thackeray, who celebrates his 86th birthday on January 23, when asked the "secret" of his good health, said, "If I reveal my secret, all these Congressmen will emulate it."