Casual apparel giant Gap Inc on Thursday posted a four per cent rise in August same-store sales and named Sears, Roebuck and Co's Nicholas Severino as divisional chief financial officer for its Gap brand.

The California-based company said same-store sales for the four weeks ended August 30 rose one per cent at both its Gap US and Gap International divisions, with comparable sales up eight per cent at Banana Republic and six per cent at Old Navy.

Total sales at its 4,212 stores and concepts increased five per cent to $1.22 billion from $1.16bn in the same month of last year.

"Back-to-school marketing helped drive strong sales of our featured Gap cords and Old Navy cargos," said Sabrina Simmons, senior vice president, treasury and investor relations.

"Banana Republic also had strong results as customers responded well to our wear-now Fall transitional merchandise."

She continued: "While we're pleased with our positive comp performance, August sales overall were slightly below our beginning of month expectations.

"Strong consumer response to advertised products was somewhat offset by weaker than expected demand for fleece activewear and long sleeve tops at Old Navy, and long sleeve tops and basic denim at Gap. Total company merchandise margins were in-line with last year."

In a separate press release, the retailer said 37-year-old Severino will oversee all financial aspects of Gap's US business and report to both Lee Bird, executive vice president and chief operating officer of Gap's domestic division, and Byron Pollitt, CFO of Gap Inc.

"I'm very excited to have Nick join our Gap team," Bird said. "Nick brings with him exceptional retail experience and will complement the brand's leadership with his financial management skills."