A man has been arrested in Delhi for allegedly trying to extort money from Samajwadi Party leader Amar Singh by posing as a senior central government official, police said on Tuesday.

B K Verma (40), a resident of Lajpat Nagar, had been making phone calls to the SP general secretary claiming that he was a senior law officer and could help him if he paid him Rs 5 crore, a senior police official said.

The man, said to be a private tutor, claimed that he was very close to an Union minister and a retired Supreme Court judge and had been calling Amar Singh and even tried to meet him when he was hospitalised last month.

Amar Singh informed City Police Commissioner K K Paul about the incident when Verma showed up at his Lodhi Road residence on Monday morning after which he was arrested by special cell officials.

Verma has been booked for impersonation and extortion of money, a senior special cell officer said.

Amar Singh in a written complaint to the police chief said there was a "bigger conspiracy behind this incident" as an "ordinary person cannot perpetuate such a fraud without the backing of someone powerful" and sought a proper inquiry into the matter.

Paul said an investigation was on into the incident.