Federal authorities investigating allegations that Lance Armstrong and other top cyclists engaged in doping are considering whether they can expand the investigation beyond traditional drug distribution charges to include ones involving fraud and conspiracy, according to two people briefed on the investigation.

The authorities, who are in the early stages of their investigation, are seeking to determine whether Armstrong, the owners and managers of his former cycling teams and his teammates conspired to defraud their sponsors by doping to improve their performances and garner more money and prizes, one of the people said.

In particular, the authorities want to know whether money from the United States Postal Service, the main sponsor of Armstrong’s team from 1996 to 2004, was used to buy performance-enhancing drugs, one of the people said. Fraud charges can carry longer sentences than charges of drug distribution.

The two people briefed on the investigation spoke on the condition of anonymity because they did not want to jeopardize their access to delicate information. Armstrong, through his manager, Mark Higgins, did not immediately respond to an e-mail message seeking comment. Armstrong has repeatedly denied any allegations about doping.