NEW YORK (CNN/Money) - The spotlight on Hewlett-Packard Corp.'s efforts to sway big investors to vote in favor of its proposed buyout of Compaq Computer Corp. got a little bit brighter Monday after the company said federal regulators and law-enforcement officials had begun an inquiry into the matter.

The company said both the Securities and Exchange Commission and the U.S. Attorney's Office for the Southern District of New York have asked for information regarding HP's March 19 shareholder vote on its takeover of Compaq.

HP said it received a subpoena from the U.S. Attorney's Office on April 10 to produce information about the voting of Deutsche Bank and Northern Trust, and their affiliated parties, in connection with the HP-Compaq merger.

At the same time, HP said the San Francisco office of the SEC asked the company informally to voluntarily produce documents and related information concerning its relationship with Deutsche Bank.

In a brief statement, HP said the inquiry arose "in response to press accounts about HP's activities leading up to the March 19 vote on the merger."

That apparently was a reference in part to last week's leak of a voice mail -- sent anonymously to a reporter at the San Jose Mercury News -- in which HP CEO Carly Fiorina tells another HP executive, "We may have to do something extraordinary for those two to bring them over the line."

But most of the recent press accounts have been generated by a lawsuit brought by dissident HP director Walter Hewlett, who is seeking to block the deal.

In a complaint filed in a Delaware court, Hewlett claims that HP executives had used "corporate assets to entice and coerce" Deutsche Asset Management to vote in favor of the proposed deal.

Essentially, Hewlett's suit argues that HP management threatened to lock Deutsche Bank, the money manager's parent corporation, out of future HP investment-banking business if it had voted against it.

Because of that pressure, Hewlett's complaint alleges, Deutsche Bank, which previously had indicated it would vote against the deal, at the last minute switched its votes in favor of it during a March 19 shareholder meeting.

A trial date has been set for April 23.

HP said the SEC has advised the company that the inquiry should not be construed as an indication that it had violated any law, adding that it is cooperating fully with both inquiries.

"We have long-standing relationships with Deutsche Bank as well as with many other institutional share owners," HP spokeswoman Judy Radlinsky said. "Some of them voted for the merger, others against, some split their votes, and others changed their minds -- in both directions. We never acted improperly. We remain optimistic that we can close the merger on our current schedule."

Deutsche Bank has refused to comment on the matter. Northern Trust's investment arm has said it did not split its vote on the deal and did not change its position in the final days.

Hewlett's lawsuit and the subsequent government inquiries are the latest chapter in what has been one of the most bitter proxy fights in recent memory.

For their part, Hewlett and his allies have argued, among other things, that by buying Compaq, HP would increase its exposure to less profitable areas such as PCs and low-end servers while jeopardizing its strong position in the printing and imaging business.

Executives of HP say that a merger is necessary in an increasingly competitive and consolidating industry and would yield annual cost savings of $2.5 billion and about a 12 percent improvement in earnings.

HP executives claimed victory "by a slim but sufficient margin" following the March 19 shareholder meeting. But Hewlett maintained the vote was too close to call.

An independent inspector of elections has not yet returned an official tally. It is expected to do so in the next couple of weeks.

Shares of HP (HWP: up $0.03 to $17.83, Research, Estimates) rose modestly in afternoon trading on Monday. Compaq (CPQ: up $0.17 to $10.15, Research, Estimates) shares were also trading in the plus column.