Shares in troubled drilling service outfit Boart Longyear slumped to all-time lows on Wednesday amid deepening pessimism over the outlook for the group and following the ongoing sell-down by one of the company's key backers.

Speculation that corporate restructuring adviser KordaMentha, along with legal adviser Ashurst, had been appointed to assist the company's ongoing strategic review put the shares under renewed pressure in sharemarket trading, prompting a suspension from trading pending clarification of a media report of the appointments.

''The scope of the strategic review has included all potential options reasonably available,'' Boart Longyear said in a statement to the ASX. ''The breadth of the options evaluated … by the company has required the participation of restructuring advisers since the initiation of the review in late February, and those advisers, along with Goldman Sachs and other advisers, continue to actively assist … the company with the range of options that remain under consideration with a number of third parties.

''The company will disclose material developments related to the strategic review at the appropriate time.''

Also putting pressure on Boart Longyear's share price was selling by Canadian fund manager Beutel Goodman, which confirmed it had turned a seller of Boart scrip, cutting its exposure by 7 million shares to 65.6 million shares in recent trading.

By the close of trading on Wednesday, the shares had fallen 36 per cent to 8.8¢, closing off the late low of 8.5¢, which values the entire company at just $40.6 million.

At its peak, the company's shares traded at more than $22.

Boart Longyear has been hit by the severe downturn in exploration and development spending by mining companies amid weak commodity prices. The impact of this has been complicated by its heavy debt burden, which has triggered concerns that it may be in breach of its debt covenants. At the end of March, net debt stood at $US544.4 million ($582.3 million).

Earlier this month, Boart Longyear confirmed that earnings may fall short of earlier forecasts, due to the ongoing contraction of the drilling services market.