NEW YORK (Reuters) - The International Brotherhood of Teamsters urged McKesson Corp's MCK.N shareholders to vote against the company's executive pay practices and called for it to appoint an independent chairman as the union criticized the drug distributor for its role in the U.S. opioid drug epidemic.

McKesson Corp CEO John Hammergren tees off on the 17th hole during the first round of the Pebble Beach National Pro-Am golf tournament in Pebble Beach, California, February 12, 2015. REUTERS/Michael Fiala

McKesson Chief Executive John Hammergren was paid more than $20 million for the year ended March 31, despite the company’s record $150 million settlement paid to resolve a U.S. investigation into whether it failed to report suspicious orders of addictive painkillers.

“Recent pay decisions ... send completely the wrong message to shareholders, regulators, lawmakers and the public about executive accountability,” the Teamsters wrote in a letter to other shareholders filed with the U.S. Securities and Exchange Commission on Monday.

The union did not disclose how many McKesson shares it owns, but said it had substantial holdings in the company.

It asked shareholders to vote against a proposal to approve executive compensation and for a proposal asking for an independent chairman. The “say-on-pay” proposal is an advisory, non-binding vote.

McKesson said in a statement the company has invested millions into and enhanced its controlled substances monitoring program.

It also filed slides defending its pay practices, noting that Hammergren’s pay had declined 27 percent over the past 4 years.

“McKesson and its shareholders have been well served during John Hammergren’s service as both CEO and chairman of the board,” the company said.

McKesson’s $150 million settlement with the U.S. Justice Department earlier this year followed an earlier settlement with the company over similar violations in 2008.

In addition to being McKesson investors, the Teamsters also represent some of McKesson’s workers.

McKesson shares were up 44 cents, or 0.3 percent, to $165.12 in midday trading on the New York Stock Exchange.