The process is designed to identify those staff least competent in dealing with the public, and is likely sharply reduce from 3,500 the number of employees handling public queries and concerns.
The move comes as British Gas attempts to recover from a barrage of criticism over falling standards of service which culminated in a warning last month that it might lose its Government Charter Mark.
The interviews will mark one of the final stages of restructuring of British Gas Public Gas Supply. By the end of June, around 11,000 staff at PGS will have undergone detailed assessments of their suitability. The casualty rate at some levels of management is said to have been very high.
Mike Alexander, managing director of public gas supply said that his aim to is have a much smaller number of employees than the 11,000 which were in place in March 1994. Any cuts are part of the British Gas aim of reducing staff across all UK gas operations by 25,000.
Mr Alexander said that unions are supportive of the interviewing process as it will result in long term employment for the right people. He added:"Training will be continuous from now on."
The new PGS is undergoing a complete culture change with power devolved through the ranks. One aim is to enable people dealing with customers at "the front line" to advise them on tariffs and services and to take decisions where customers have a grievance concerning their bills. The management structure of the gas supply company has also been changed with six layers replacing the previous 13.
British Gas has been at the centre of controversy since last November when it emerged that the company had agreed a 75 per cent increase in basic pay for the chief executive, Cedric Brown. About the same time, there was an outcry over plans to stop payment of gas bills at showrooms. There was also a furore over a decision to introduce discounts of five per cent for all those who pay by monthly direct debit.
The changes resulted in a sudden increase in the number of enquiries to British Gas and the company's system for handling telephone queries and correspondence was unable to cope.
Mr Alexander said that measures are now in place to resolve the problem. He has repeatedly rejected the suggestion that PGS might lose its Charter Mark.
British Gas is faced with competition in domestic gas supply from April next year when a pilot scheme begins in the south west. The pilot will be extended in 1997 with full competition expected to be in place by the end of 1998.