SAN JOSE — The chief executive of Polycom, Andrew Miller, resigned Tuesday as the top boss of the videoconferencing company after irregularities were allegedly discovered in his expense reports.

Details weren’t disclosed about the nature of the irregularities, which were uncovered by the audit committee of Polycom’s board.

San Jose-based Polycom named Kevin Parker as interim CEO. Miller had been at the helm of Polycom for four years.

“Andy Miller’s resignation under these circumstances is disappointing and should not be viewed as a reflection of the financial integrity of the company, the strength of our team or our plans for the future,” Parker said in a prepared release.

Polycom’s shares fell 5.6 percent in after-hours trading. In the regular trading session, Polycom fell 4 percent, or 47 cents a share, to finish at $11.18.

“This will be a huge loss for Polycom,” said Rob Enderle, principal analyst with San Jose-based Enderle Group, which tracks the tech sector. “People at Polycom really liked Andrew Miller. He created a nice working environment. Polycom has been doing pretty well.”

Even with the departure of Miller, according to Enderle and technology analyst Michael Tchong, Polycom should be able to preserve much of its momentum in videoconferencing equipment and services, and collaboration from a distance.

“Polycom has a dominant brand,” said Tchong, founder and principal analyst with San Francisco-based Social Revolution, which tracks innovation and digital trends. “Their brand is so strong that Polycom is a fixture in just about every conference room. They should be able to overcome this.”

Among Polycom’s chief rivals: San Jose-based networking giant Cisco Systems (CSCO).

Miller’s departure, as well as the company’s quarterly financial results, were announced after the stock markets had finished trading Tuesday.

The company’s financial results topped Wall Street’s expectations.

In the second quarter that ended in June, Polycom earned $5.3 million on $345.2 million in revenue. Excluding one-time items, Polycom’s per-share earnings were 15 cents. Wall Street had predicted revenue of $341 million and 14 cents a share.

During a conference call with analysts to discuss the results Tuesday, Parker acknowledged the challenges involved with Miller’s exit.

“This is a tough set of circumstances,” Parker said. “But the focus is to keep the company moving forward. Our team is very committed. We have a terrific team.”

Contact George Avalos at 408-373-3556 or 925-977-8477. Follow him at Twitter.com/george_avalos.