SYDNEY — Qantas Airways, Australia’s struggling flagship carrier, canceled orders for 35 Boeing Dreamliner jets Thursday to cut costs further after posting a full-year net loss for the first time in 17 years because of its troubled international division.


Qantas shares jumped to their highest price in more than two months as investors welcomed moves by the airline to reduce costs after a year troubled by a record fuel bill, rising competition and a labor union that has opposed the carrier’s spending cuts.


The airline, which had earlier warned of a net loss, reported a shortfall of 244 million Australian dollars, or $254.8 million, in the 12 months that ended June 30.


The airline’s chief executive, Alan Joyce, declined to give any predictions for earnings in the current year, citing volatility, but he said the airline remained committed to reaching break-even in its international business in the 2015 fiscal year.


“Given lower growth requirements in this uncertain global context,” Qantas is canceling orders to buy the 35 Boeing 787-9 jets, Mr. Joyce said.


The cancellation will result in an unspecified “reduction in our forward capital expenditure commitments,” he said, noting that the aircraft were worth a total of $8.5 billion at list prices.


“There is not a lot of flexibility left in the Qantas balance sheet, and with their operating performance, they have not many options left to conserve capital other than by delaying or canceling orders and staying with an older fleet, ” said David Liu, head of research at the fund manager ATI Asset Management, which sold all of its Qantas holdings during the past two months.


“Most of the canceled aircraft were meant for the overseas routes, and with the trading environment for their international operations, it is not surprising,” Mr. Liu said.


Qantas currently has a fleet of 308 aircraft. Options and purchase rights for another 50 Boeing 787-9 aircraft will be moved to 2016, Mr. Joyce said. The moves mean a two-year delay in the delivery of the carrier’s first 787-9s.


The cancellation is a blow for Boeing, based in Chicago, which said in a news release that it stood by Qantas as a “long-standing and valued Boeing customer.”


Qantas will still take delivery of 15 Boeing 787-8s, the smaller variant of the wide-body, twin-engine jet, for its Jetstar subsidiary toward the second half of 2013, Mr. Joyce said.


On Thursday, Qantas posted a second-half underlying loss before tax of 107 million dollars, compared with a profit of 135 million dollars in the same period a year earlier.


The airline, which has embarked on a five-year turnaround strategy announced last year, is separating its unprofitable international business from its profitable domestic unit, eliminating unprofitable routes, cutting 2,800 jobs and reducing capital spending over two years by 700 million dollars.


The cost-cutting measures have been opposed by unions, and the airline is emerging from a bruising labor dispute that led to the grounding of its entire fleet for nearly two days last year.


But investors had been looking for signs that Qantas was managing its costs, particularly the fuel bill, which the carrier had warned would be its highest ever in the 2011-12 business year.


The bill came in at 4.3 billion dollars, up 18 percent from the previous year. Qantas forecast underlying fuel costs for the first half of 2012-13 at 2.3 billion dollars, suggesting the potential for another record year of losses.


“There’s no silver bullet, there’s no easy fix, there’s no exit here that’s going to solve it,” Mr. Joyce told reporters. “But we are committed to it.”


Shares in Qantas had risen 6 percent to 1.24 Australian dollars by midafternoon.


Mr. Joyce, who confirmed this week that he would not receive a bonus this year, said Thursday that the airline was continuing “to work on building up partnerships.”


The earnings announced Thursday were the last to be posted by Qantas in its current form. The airline will split its domestic and international operations into separate reporting units at the start of the 2012-13 business year.