New Delhi: Congress chief Sonia Gandhi has had to rush to the United States along with son Rahul Gandhi to attend to her ailing mother who is said to be undergoing a series of medical tests there.

This is the reason for her absence in Parliament as well as not being able to meet visiting UK Prime Minister David Cameron.

Rahul Gandhi was also to be part of the meeting with Cameron. But these engagements had to be hurriedly cancelled.

While her absence has generated much speculation, sources said, the Gandhi family had to leave in a hurry and possibly left sometime during the last weekend. Priyanka Vadra is also said to have accompanied her mother and brother.

Sonia's mother Paola Maino is in her 80s and her illness has apparently been complicated by age-related problems. Though she stays in the family home at Orbassano in Turin, she had, of late, been living for long periods in New Delhi.