Safety on the Tube network is being undermined by the obsessive secrecy of the private company at the centre of the Camden Town derailment incident, according to London's transport chief.

Bob Kiley, the capital's transport commissioner, claimed the refusal of the infrastructure and engineering consortium Tube Lines to supply vital information to London Underground was dangerous.

Mr Kiley's remarks come ahead of the announcement tomorrow of the result of a strike ballot over safety among 8,000 members of the RMT rail union at London Underground. Senior officials of the union are predicting a "yes" vote amid deep concerns about the ability of a highly complex partly privatised structure to run the underground network safely.

Mr Kiley said the Tube Lines consortium, which counts the beleaguered Jarvis Rail company among its members, was failing to hand over vital data about maintenance work.

The commissioner pointed out that such secrecy meant that one part of management did not know what the other was doing.

He said relations between Tube Lines and London Underground, the state-backed organisation which still runs the trains, were "strained". Transport for London found that the network was "extremely hard to manage" and this had potential implications for safety, he added.

He said: "We are often involved in theological arguments which are getting in the way of good management. It is sometimes difficult to know what's going on. This is a dangerous state of affairs."

He said that while it is too early to arrive at a final assessment of the new Public-Private Partnership (PPP) which runs the system, contracts which govern the work undertaken by the two infrastructure consortiums might have to be rewritten.

Tube Lines took over the maintenance of the Northern line, together with the Jubilee and Piccadilly routes on 31 December last year. In the summer a second consortium, Metronet, assumed responsibility for the rest of the system. Mr Kiley said it was too early to assess Metronet's performance in running its lines.

Concern over safety deepened last month after two trains derailed in as many days. On 17 October a Piccadilly line train came off the track between Hammersmith and Barons Court. Two days later, seven people were injured when a Northern Line train derailed and hit a wall just outside Camden Town station. It is thought defective points maintained by Tube Lines were to blame for the incident.

All stations are now open on the line, but the service is still limited. It is thought that the consortium could face fines of up to £40m for the disruption caused. The penalties are mounting at the rate of £4.5m a day under the terms of the group's contract with London Underground.

Mr Kiley pointed out that apart from the PPP, specific projects have been undertaken under the Government's private finance initiative on the Tube, increasing the complex nature of the system. The Transport commissioner and the Mayor of London, Ken Livingstone, took legal action last year in an attempt to stop the PPP going ahead, but failed.

A spokesman for Tube Lines said the disagreement with Transport for London had nothing to do with safety. "We do not compromise on the safety of passengers," he said.

He claimed Tube Lines had supplied more information than it was obliged to provide and Transport for London was effectively trying to renegotiate contracts.

"Some of the information they are asking for almost comes down to queries about the cost of grouting for tiles. They are trying to limit our freedom to manage," he said.