Engineering group Melrose has warned of a slowdown - particularly hitting its energy businesses - which sent its shares plummeting.

The Alcester-based Industrial investment firm revealed the hit last week - sending its shares down as much as 16 per cent to a 10-month low.

Its energy-related businesses account for about half its operating profit, sending its shares down as much as 16 percent to a 10-month low.

The company also admitted that prospects for German meter maker Elster - acquired earlier this year for about s1.5 billion - had been affected by lower-than-expected demand.

"Growth in energy will be more modest next year, so I think that will be the division that we're most cautionary on," finance director Geoffrey Martin said.

"We're not talking about revenue decline, we're not talking about things going backwards, just more modest growth going into next year."

Melrose follows a private equity-type model of investing in companies with the aim of improving their performance and selling them on.

In a trading statement, the company said the outlook for next year was unclear.

Melrose said its overall weekly rate of order intake in the period from July 1 to November 15 was eight per cent lower than the first half, excluding results from Elster.

It states: "Trading is in line with expectations for 2012, although revenue trends have slowed and recently the sales outlook for 2013 has become more uncertain."

Revenue, excluding Elster, grew six per cent at constant currencies in the period through November 15, compared with 10 per cent in the first half.

Melrose owns businesses that cater to the energy, oil and gas and mining industries, as well as manufacturing firms that serve the housing, construction and automotive sectors.

In June it bought Elster Group in its first major deal in four years.

"We have already made significant changes to Elster, and identified larger than expected cost savings," the firm said, adding that a restructuring announced by Elster at the beginning of the year was on track.

The announcement last Friday saw shares fall 16 per cent to 198.2p, their lowest since January, before recovering slightly.