Tube bosses were told to widen safety checks six months ago

Safety concerns for London Underground reached new heights last night after leaked documents revealed deficiencies in the inspection and maintenance of its tracks.

Despite the fact the network was ordered to step up its testing as long as six months ago, thousands of examples of "substantial non-compliance" were highlighted in a confidential document compiled by the Health and Safety Executive before the introduction of the Government's part privatisation of the Tube.

The HSE served an improvement notice to the network stating that its variable standards of engineering inspections of its tracks had resulted in an inevitable "cycle of deterioration".

In response to the report, completed in May, London Underground admitted there were problems stating "manual track assessment is not being done at the required frequency due to lack of competent staff".

The documents, which were leaked to the BBC, confirmed fears the Underground network was deteriorating well before partial privatisation of the network took place in July.

In the aftermath of two derailments earlier this month, the findings are poised to reignite concerns over the standards of maintenance.

Seven people were injured at Camden Town station when the rear carriage of a Northern Line train came off the track and hit a wall. Two days earlier, a Piccadilly Line train derailed at Hammersmith, reportedly due to a cracked rail. The delays and cancellations caused chaos for commuters trying to get in and about the capital city,

After the incidents, which are being investigated, London Underground stated that inspections procedures in place at the time were adequate. The report, leaked to the BBC programme Kenyon Confronts, contained the findings of a wide-reaching inspection of the network conducted by the HSE immediately before part privatisation in February and March this year.

The conclusions of the report revealed that, while certain Tube workers adhered to the inspection regime, others viewed the process as "a necessary nuisance".

Describing the state of the track, the HSE inspectors concluded: "The overall picture is of staff struggling to maintain and improve an inherited asset in poor condition,

It added: "Large amounts of resources are diverted for patching up sub-standard components. That erodes resources available for preventative maintenance and contributes to a cycle of deterioration."

Following the two derailments, the network has said that it is considering increasing ultrasonic testing on the tracks in a bid to increase the detection of broken rails. A London Underground spokesman said: "Safety is and will remain a priority for London Underground. We are currently reviewing maintenance standards in the technology involved, including ultrasonic testing."

Transport unions are also expected to seize upon the findings of the leaked HSE report having long campaigned for improvements to safety standards on the Tube.

The Rail Maritime and Transport union is planning to ballot for industrial action after its demand for track inspections every 24 rather than 72 hours was rejected. It is also expected to instruct its members not to drive trains faster than 24kph (15mph).

"Declining safety standards can be traced to preparations for privatising Tube infrastructure," said a spokesman for the RMT.