The chairman of CIE, Dr John Lynch, has warned unions and management at Dublin Bus that there can be no return to the dark days of unofficial action and lightning strikes at the company.

Dr Lynch, in a strongly worded letter to be issued to management and unions this week, says last Tuesday's stoppages, which caused major disruption in large parts of the city, must not be repeated.

He has instructed the management of Dublin Bus, plus the two main unions NBRU and SIPTU, to carry out an immediate investigation into the events that led to Tuesday's lightning strike.

In the letter Dr Lynch asks all parties to thoroughly examine their existing policies and procedures that deal with issues of assault, sick pay and grievances. He wants management and unions to identify what went wrong with these procedures and why "disruptive and unwarranted strike action" took place.

He is also demanding that where failings are identified, new procedures should be immediately drawn up between both parties, agreed on and implemented straight away.

"We have worked extremely hard to make lightning strikes a thing of the past," Dr Lynch said. A spokeswoman said the company and the chairman did not want to see a return to the "dark days" of the past when stoppages were a regular occurrence.

Unofficial strike action caused a four-hour disruption to bus services from the Ringsend depot on Tuesday. Services to Terenure, Templeogue, Tallaght and Blessington were all affected due to the disruption. Full service resumed at 10 a.m. without any concessions from the company. Tens of thousands of passengers were without a bus service for the morning.

The unofficial action related to an incident affecting one bus driver which took place on Friday, September 24th. at 10.30 p.m. near the Halfway House, Walkinstown. The driver claimed that a passenger urinated on him during the incident. This driver set up a one-man picket at Ringsend on Tuesday morning to highlight this issue and what he said was a loss of overtime. As the morning progressed drivers would not pass his picket and there was a loss of service.

On September 12th there was also unofficial strike action, this time over the relocation of a terminus, which affected routes based at Conyngham Road garage.