SHARES in Petrofac plunged 17% after the oil services giant said it expected little or no growth next year and triggered doubts among investors about whether it would meet targets for the following year.

But Petrofac, which employs 4200 people in Aberdeen, showed it has continued to cash in on booming activity levels in the North Sea.

Petrofac sparked alarm with an Interim Management Statement in which it highlighted complications on some flagship overseas contracts. The London-listed company helps firms develop and maintain oil and gas assets and invests in some of them.

The company said: "We expect group net income in 2014 to show flat to modest growth year-on-year reflecting the re-phasing of both the Upper Zakum project in Abu Dhabi and the second stage of the Berantai project in Malaysia."

With some income from both projects now likely to be deferred beyond 2015, Petrofac faces a struggle to meet its target for that year's earnings.

The company has said it wants grow net income to $862 million (£535m) in 2015, from $431m in 2010.

Petrofac warned the achievement of that target would also be dependent on the timing of potential contract awards.

The tone of the update contrasted with the guidance Petrofac issued with its interim results in August.

Chief executive Ayman Asfari said then: "Our high-quality portfolio of existing projects... together with a strong pipeline of bidding opportunities and our competitive positioning means that we remain on track to achieve our 2015 earnings target."

The company reported a 25% fall in first-half net profit to $243m in the six months to June, from $326m in the first half last time.

Petrofac said it expected to achieve modest growth in earnings in 2013.

Yesterday's update highlighted the challenges companies may face meeting investors' expectations when working on projects of the scale of those on the huge Upper Zakum and Berantai fields.

Andrew Dobbing, analyst at joint house broker JP Morgan Cazenove, told clients of the brokerage that Petrofac had delivered "disappointing news for medium-term earnings".

However, Petrofac noted the revised phasing of the Upper Zakum project was connected with studies that could increase the scale and length of the project.

The phasing of elements of the Beranta project has been changed but Petrofac is not late with any work.

Petrofac said the offshore projects and operations division, which works on existing assets in areas such as the North Sea, "continues to perform well".

The company said it recently won a number of contract extensions in the North Sea, where oil and gas firms are trying to boost output to meet strong global demand.

In August, Petrofac said its UK business was very robust, "with increased levels of activity from core clients such as Apache, Enquest and CNR".

Petrofac is working on a big contract to build a gas processing facility on the Shetland mainland to handle production from Total's giant Laggan Tormore development off the isles.

The company expects to capitalise on continued strong activity levels around the world.

It recently secured a $650m project for the Alrar gas field in Algeria, with joint venture partner Bonatti.

The group had an order book worth $14.3bn at 31 October, in line with the level in June.

Mr Asfari said: We remain confident of the long-term growth trajectory for Petrofac."