The pounds 360m hostile bid by the Norwegian engineer for the UK contractor closes at 1pm today, with analysts saying the outcome is too close to call.
Kvaerner said the last-minute intervention by the MP, who as a minister worked closely with Amec's chairman, Sir Alan Cockshaw, was surprising and unwelcome.
In a letter in Saturday's Financial Times Mr Needham, who recently became a director of GEC, said the UK would be "severely disadvantaged" without companies like Amec to win exports. He was particularly concerned about the impact Amec's loss of independence might have on relationships with countries in the Far East.
An Amec adviser said Mr Needham had simply pointed out that the company was world-class. But with the bid finely balanced, Kvaerner reacted strongly, arguing that Amec's track record in the Far East was not so remarkable.
"Amec's international operations would remain in London after the takeover," said Kvaerner yesterday. "We work closely with many UK companies, including Amec. And Kvaerner has invested pounds 100m in the UK."
The bid was left hanging in the balance at the end of last week as Norwich Union sold its 2.6 per cent stake in Amec, leaving Kvaerner sitting on 26 per cent of its target. Some other big shareholders, including M&G with 8 per cent, lined up behind Amec.
The outcome will depend on small shareholders, holding around 20 per cent of Amec, and on PDFM, the fund management offshoot of Union Bank of Switzerland, which holds 14 per cent.
The bid has been marked by more than the usual degree of acrimony. Amec sacked its public relations advisers after they were heavily censured by the Takeover Panel. There has also been criticism of the tactics employed by Kvaerner in pursuing the bid. M&G hit out at the use of a seldom-used rule to cut the bid timetable from 60 days to just 21. Another institution was critical of the dawn raid which netted Kvaerner's original 10 per cent stake in Amec.