Shares in the FTSE 100 company rose 3.2 percent to 1020 pence in early trade on Friday on the London Stock Exchange. They were the top percentage gainers on the index.

Group backlog was $21.2 billion (13.18 billion pounds) as on Sept. 30, compared with $20.3 billion at the end of June, the company said in a statement.

"With activity levels stepping up over the second half of the year, in line with our expectations, we remain on track to deliver net profit in the range $580 million to $600 million for the full year 2014," Chief Executive Ayman Asfari said.

Petrofac said its pipeline of bidding opportunities at its engineering and construction business, which accounts for nearly 60 percent of total revenue, remained strong, with customers investing heavily across its core geographies.

The company, which builds and maintains oil and gas facilities, had earlier said its results would be heavily weighted towards the second half of the year.

Petrofac has struggled with operational issues and delays at key projects in the first half of 2014, with profit for the period nearly halving.

The company said its operations in Iraq continued to be insulated from the unrest in the region. Iraq accounts for less than 5 percent of its annual revenue.

Petrofac's shares have fallen nearly 18 percent since May when it cut its full-year profit forecast by 11 percent.

(Reporting by Abhiram Nandakumar in Bangalore; Editing by Gopakumar Warrier)