STEPHEN BYERS, the Trade and Industry Secretary, took the rare step of releasing minutes of a private conversation with BMW executives yesterday as he tried to shore up his ministerial authority amid union unease and Conservative demands for his dismissal. Mr Byers authorised officials from his Department of Trade and Industry to go public on the talks six days before the sale of Rover was announced, in an attempt to show that he could not have forseen the decision. He had promised to lay the details before the Trade and Industry Select Committee next week, and his decision to go public earlier was seized on by the Tories as evidence of his nervousness. He won room for manoeuvre when BMW admitted that it had not warned Mr Byers that Rover's future was in jeopardy, despite the firm's earlier insistence that it had. Joachim Milberg, BMW's chairman, said he had told Mr Byers that BMW would have to reconsider the development of a new model at Longbridge if the company did not get European Union approval for £152 million of grant aid. He had told Mr Byers: "If the structural aid is not approved, the BMW Group has to reconsider its investment plans for the R30 at Longbridge." But he stopped short of saying that BMW could quit the UK. However, Tories said that "R30" was bound up with the future of Longbridge, and that Mr Byers should have known what the warning meant. John Redwood, the former Tory industry spokesman, said the Trade and Industry Secretary was "clearly a very rattled man". Trade unions also failed to give Mr Byers a vote of confidence over his handling of the issue when they went into Downing Street for talks with the Prime Minister yesterday. John Edmonds, general secretary of the general GMB union, urged Mr Blair to "personally get a grip" of the Rover issue. Mr Edmonds, in advance of the meeting, said: "This issue has become of such great importance to the economic programme of the Government that it needs Blair personally to take control." Officials said that Mr Byers had met Professor Werner Samman, head of Rover UK, on March 10, when the executive had laid out four steps that BMW could take to stem the losses of £2 million a day being suffered by Rover. They included increasing production dramatically, taking more components from overseas suppliers, concentrating on car assembly, and reducing production of the Rover 25 and 75 models. However, they also revealed that Mr Byers had not asked directly whether BMW were considering selling Rover. A DTI official said that it would have taken a "leap of imagination" to pose such a question when BMW's four options had been outlined.