Toys R Us said it plans to hire about 45,000 seasonal workers—10,000 more than in the past three years—ahead of the U.S. holiday shopping season as it opens 600 temporary stores, essentially doubling its domestic workforce.

Of the new hires, 35,000 will staff 587 traditional Toys R Us stores, while the others will fill 10,000 already-announced positions at 600 Toys R Us Express temporary stores in malls and shopping centers, the world's largest dedicated toy retailer said late Monday.

The news comes a week after department store chain Macy's said it planned to hire about 65,000 seasonal staff for the holiday season—a slight increase from previous years.

The rise in hiring reflects Macy's (NYSE:M) expectation that same-store sales will grow 3% to 3.5% in the second half of fiscal 2010, the company said in a statement.

Some of the optimism on hiring can be tied to the recent improvement in sales.

U.S. retailers posted their largest sales gain in five months in August on strong receipts at gasoline stations and clothing outlets, easing fears of a double-dip recession.

Last year, retail payrolls grew by 501,400 workers in October, November and December, according to data from the Bureau of Labor Statistics.

That was a 30% increase from 2008, when holiday hiring fell to a 22-year low of 384,300 extra holiday helpers in the wake of the global financial crisis.

Some industry watchers such as consultancy Challenger, Gray & Christmas Chief Executive John Challenger expect U.S. retailers to hire more seasonal workers this year, but said the amount of temporary staffing will not approach pre-recession levels.