The boss of National Express East Anglia has stepped in to improve the lot of passengers repeatedly hit by delays caused by engineering works, after condemning the poor track record of Network Rail in upgrading the key London to Norwich line.

Passengers last week faced delays of up to 75 minutes after weekend engineering works over-ran, causing day-long delays on services into the Liverpool Street, while similar problems saw some trains again delayed on Monday for around 15 minutes.

In an email to MPs in Norfolk, Suffolk and Essex, seen by the EDP, Andrew Chivers, managing director of National Express East Anglia, criticised the performance of Network Rail and said its progress in reducing delays caused by infrastructure over the last seven years had been 'minor' compared to the rail operator's record in tackling delays casued by train faults.

And he said the firm had also taken action to get Network Rail to focus more on the needs of passenger, but warned that 'difficult days' were likely to continue for the next few weeks.

It comes barely a week after a report by the House of Commons Public Accounts Committee warned that passengers in the East of England faced years of overcrowding after the government had failed to meet targets to increase seats available on services into London.

As well as over-running engineering work last week, Mr Chivers said it had also emerged that 'some of the additional infrastructure problems on Tuesday and Wednesday resulted from sub-standard installation of equipment during the same weekend engineering work programme'. 'Network Rail have already carried out an initial investigation, which suggests that the key causes of the problems related to poor project management, inadequate programme preparation and unsatisfactory real time delivery of the works by the contractors...,' Mr Chivers said. 'They are taking steps to ensure that better planning and monitoring of such schemes is in place for future projects.

'We have acted quickly to raise our concerns with the Network Rail Route Director, Andrew Munden. In addition, our group chief executive Dean Finch has also met personally with the Network Rail Chairman, Rick Haythornthwaite, to emphasise just how damaging such disruption is for our passengers and to highlight our wider discontent that the rate of performance improvement and overall punctuality standards being achieved by Network Rail on the Great Eastern Mainline are not acceptable. Their progress in reducing infrastructure-related delays over the last seven years has been minor in comparison to the major reduction we have achieved in delays caused by train faults.'

He added that National Express East Anglia had also appointed a manager to work at the joint control centre in London, and would co-locate teams at Network Rail depots to increase the urgency in Network Rail's decision-making and create a 'greater focus on passengers' needs'.

Last night, North Norfolk MP Norman Lamb said he had written a joint letter with Lib Dem colleague Simon Wright seeking an urgent meeting with Network Rail.

'There appears to be clear failures on the part of Network Rail, which is being confirmed by the operating company,' Mr Lamb said. 'It's intolerable; we can't put up with that level of service disruption.

'You just think of the loss of productivity,' Mr Lamb added. 'The impact that this has is enormous. Everybody using this line is sick of these problems occurring. Network Rail's performance isn't good enough.'

South Norfolk MP Richard Bacon said the email raised further questions about the ability of the Office of Rail Regulation to oversee the work of Network Rail.

'Why should rail travellers have to put up with poor project management and inadequate preparation just because Network Rail can't get its act together,' Mr Bacon said. 'This highlights the need for Network Rail to be properly regulated and I regret to say that the Office of Rail Regulation has not done a good job'.

A Network Rail spokesman apologised for the disruption to customers and said the firm fully understood and appreciated the impact it had on passengers, but said it should be seen in the light of improving performance.

'In partnership with National Express East Anglia, we are introducing a number of changes to the way we manage improvement work, including better planning and stricter monitoring of work being delivered by contractors,' he said. 'We expect these changes to bear fruit immediately. At the same time we will continue to work with National Express East Anglia to ensure that once incidents are resolved, trains are able to resume a full service as quickly as possible.

'Despite the problems affecting train performance in the last couple of weeks, the punctuality of National Express East Anglia services has risen each year for the last four years. Last month, almost 19 out of 20 trains arrived at their destination on time, the best ever month for National Express East Anglia since the franchise started.'

National Express spokesman Jonathan Denby said the rail firm wanted to take pro-active steps to improve the situation and it was important to both apply pressure on Network Rail and work in partnership.