As U.S. fast-food workers on Thursday walked off the job to demand higher pay, Burger King, McDonald's and other restaurant advocates defended current wages.

Entry-level jobs open the door for employees to move into positions with better wages and greater responsibilities within and outside the restaurants, these burger giants and organizations including the National Restaurant Association maintained. They also said few employees earn minimum wage and third-party franchisees often set the pay.

More than 99 percent of Burger King restaurants are owned by third-party franchisees while the corporation McDonald's USA only runs fewer than 10 percent of the 14,000 McDonald's restaurants, according to the companies.

"Our history is full of examples of individuals who worked their first job with McDonald's and went on to successful careers both within and outside of McDonald's," McDonald's said in a statement in response to the employees' demonstrations.

Burger King declared its "restaurants have provided an entry point into the workforce for millions of Americans, including many of the system's franchisees who began their careers working at local Burger King restaurants."

As widely reported Thursday, workers at fast-food joints in cities across the country walked off the job in rebellion because they are displeased with current wages. The Service Employees International Union cited strikes in 60 cities from Los Angeles to New Orleans to West Haven, Conn.

The minimum wage under federal law is $7.25, although 19 states and the District of Columbia mandate higher pay.

According to a  letter online in support of the strike, Burger King, Domino's, KFC, McDonald's, Papa John's, Pizza Hut, Taco Bell and Wendy's enjoyed combined 2012 profits of $7.35 billion.

"Yet you still paid most of your workers less than $11,200 a yearpoverty wages," the letter declares. "It's shameful. And outrageous."

The disgruntled employees at fast-food restaurants including Taco Bell and Wendy's are said to be demanding more than twice the federal minimum wage: $15 per hour. (Taco Bell and Wendy's on Thursday did not respond to requests for comment).

Martin Rafanan, a community organizer in St. Louis, told Reuters local employees of McDonald's and Wendy's can't get by on their salaries.

"If you're paying $7.35 an hour and employing someone for 20, 25 hours a week, which is the average here, they're bringing home about $10,000 a year. You can't survive on that," he was quoted as saying. Missouri pays a minimum wage of $7.35.

The National Restaurant Association maintains just five percent of the nation's restaurant employees earn the minimum wage.

"Beyond teen-agers and some part-timers, most restaurant workers make more than minimum wage, and can work their way up to management-level and corporate-level positions that provide rewarding career paths," National Council of Chain Restaurants Executive Director Rob Green said in a statement.

But there are relatively few opportunities in the fast-food business to move up into management, according to an analysis of Census Bureau data from the National Employment Law Project (NELP).  Only 2.2 percent of positions are managerial or corporate jobs; cashiers, cooks and other crew members who work in front-line positions comprise about 89 percent of all jobs in the industry, NELP reports.

These front-line employees earn a median wage of $8.94 per hour, according to NELP. That's roughly the same amount as Oregon's minimum wage ($8.95) and 25 cents less than the standard in Washington, which is the highest-paying state for low-wage workers with a minimum wage of $9.19. (Oregon is No. 2).

Thirty one states have either no minimum wage (Arkansas, Georgia, Minnesota and Wyoming) or one that is equal or less than the federal standard, according to the U.S. Department of Labor. That means fast-food workers and other low-wage employees who are not exempt from labor standards could be working for as little as $7.25 an hour, or roughly $15,000 a year if they are employed full-time.

Federal legislation to raise the minimum wage to $10.10 was introduced earlier this year by Sen. Tom Harkin (D-Iowa) and Rep. George Miller (D-Calif.).

The last increase to the federal minimum wage became effective roughly four years ago.