FARNBOROUGH, England, July 20 (Reuters) - Philippine Airlines confirmed 15 firm orders for Boeing BA.N 787-10s on Monday, with purchase rights for another five of the widebody jetliners.

If the airline buys all 20, the deal is worth about $3.4 billion, based on estimated prices after discounts, according to IBA Group, an aviation advisory company.

The planes will have GE Aerospace GEnx-1 engines, said a source familiar with the order. Deliveries are slated to begin in 2031.