* Toys R Us to add 45,000 seasonal jobs versus 40,000 in 2011 * Outplacement firm sees slightly higher seasonal job gains * Hiring to remain below pre-recession levels-Challenger, Gray Sept 25 (Reuters) - Toys R Us on Tuesday said it would hire 45,000 seasonal employees for the upcoming holiday shopping period, becoming the latest retailer to increase its hiring in anticipation of a modest bump in consumer spending. The toy store hired about 40,000 seasonal workers last year, roughly 15 percent of whom were kept on after the period ended. Last week, Wal-Mart Stores Inc said it planned to hire more than 50,000 seasonal employees to work at its Walmart stores in the United States, slightly more than last year, while department store operator Kohl's Corp said it would hire 52,700 people, or 10 percent more than last year. The increase in hiring comes as shoppers continue to spend more in stores than they did a year ago, helped by the gradually improving economy. While the number of seasonal jobs added this year is likely to be slightly higher than a year ago, it will still trail levels seen before the recession, as retailers exercise caution when it comes to hiring, according to outplacement firm Challenger, Gray & Christmas Inc. "Look for many to start at last year's levels and hire additional workers only if strong sales early in the season warrant it," John Challenger, chief executive of Challenger, Gray & Christmas, said on Monday. Challenger's firm expects the number of seasonal retail jobs this holiday season could approach 700,000, up from 2011, when chains added just over 660,000 seasonal staffers. Back in 2006, retailers added nearly 747,000 seasonal staffers, while in 1999 nearly 850,000 workers joined the seasonal ranks, Challenger said. Research firm ShopperTrak this month forecast U.S. retail sales would rise 3.3 percent this holiday season, while consulting firm Kurt Salmon expects a 4.2 percent increase. Retailers typically add staff in the weeks leading up to the holidays to work in stores and to help in other areas, such as distribution and fulfilling online orders. Some of the increase arises from a need for more staff at the retailers' distribution centers to help quickly deliver online orders and compete with online retailers such as Amazon.com Inc. Not all retailers are adding a greater amount of seasonal staff. Target Corp plans to hire about 80,000 to 90,000 seasonal employees for its stores and distribution centers. While Target plans to hire fewer than the 92,000 it brought on in 2011, it said that 30 percent of those who were hired to work during last year's holiday season were then given year-round positions.