Mumbai: Criticising the government for telling the Supreme Court that all information on black money stashed abroad can't be disclosed, activist Anna Hazare on Saturday wrote to Prime Minister Narendra Modi and threatened to launch an agitation if the ill-gotten wealth was not brought back.

"Bringing back black money is an important issue before the nation. If needed, I won't shirk from organising an agitation on this matter," he said in the letter.

Reminding Modi of his promise made during Lok Sabha poll campaign about bringing back black money once voted to power, the Gandhian voiced displeasure over the government submitting before the Supreme Court that all information on it received from countries with which India has Double Taxation Avoidance Agreement (DTAA) cannot be disclosed.

"I have undertaken many agitations in the last 35 years. They were not against any party or individual but for the benefit of society and country," he said, adding "you (Modi) have a vast experience in power. I am a fakir and don't have any wealth. I will live and die for the country."

Hazare also said he had written to Modi on the issue of Lokpal in August but was still to receive a reply.