MINNEAPOLIS — United Airlines said on Monday it would bring its flight attendants up to the pay scale of their counterparts at Continental Airlines in exchange for changes in work rules.

Airline labor negotiations are often a tug-of-war over wages versus benefits and work rules, which both sides value as much as straight cash.

Some experienced flight attendants would get raises of more than 10 percent if they were brought up to the pay of those at Continental, wrote Doug McKeen, United’s senior vice president for labor relations, to the head of the airline’s flight attendant union. In exchange, United wants concessions such as more flexibility over which hotels flight attendants stay at, and reductions in benefits earned by flight attendants who trade away their flying time.

“The reason Continental can afford to pay these rates is that Continental currently enjoys significant advantages over United in the areas of work rules and benefit costs,” McKeen wrote in the letter dated Saturday and released on Monday.

The letter said United was proposing to use Continental’s contract “as a basis” for a new agreement at United. It said United was ready for discussions focused on the Continental contract, or other talks “to move the negotiation forward in a positive way.”

United has not made a formal wage proposal, said Greg Davidowitch, the head of the United branch of the Association of Flight Attendants-CWA, in a prepared statement.

United flight attendants took sharp pay cuts before the airline emerged from bankruptcy in 2006. Negotiations on a new contract began a year ago Tuesday.

“Flight attendants are sick and tired of waiting for the compensation and working conditions we are due,” he said. “We will not agree to the wholesale destruction of portions of our contract to pay for any perceived improvements.”

United flight attendants plan to picket at 15 airports on Tuesday — including Chicago, Frankfurt, Tokyo, Denver, and San Francisco — to protest the lack of a new agreement.