The promise came after a "put up or shut up" order from the panel, concerned about the potential for the bid to disrupt BICC's business. On Tuesday the panel said Wassall must either go hostile or cease making informal takeover offers for the group by 1pm yesterday.
The group has in the past five months said it is willing to make informal offers of 90p and 110p for BICC. On Thursday, less than a day before the deadline, it raised the figure to 125p. Yesterday the bid was formally rejected by BICC.
"The requirement comes under rule 35 [of the takeover code] and it is true to say it is a put-up-or-shut-up type of provision. There is obviously a phoney war which has been going on for some time, which leads to uncertainties for the offeree company," said a panel spokesman.
The panel's immediate concern stemmed from the forthcoming 4 May extraordinary meeting being held by BICC to approve the pounds 275m sale of its energy cables business. Wassall wants to buy all of BICC.
Wassall indicated it believed it still had a hope of winning shareholders' favour. But it is now barred from making further informal offers. Alan Jones, chief executive of BICC, said: "This stops them stalking us and it means the issue now is whether we should complete the transactions on the table."
Shares in BICC rose from 107.5p to 108.5p, while shares in Wassall fell 9p to 249.5p.