Vero said in a statement it would make a further announcement in "due course".
Pentair's 170p-a-share offer for Vero tops the pounds 94.4m recommended bid at 157p-a-share from Applied Power. Pentair said it was seeking a recommendation from Vero.
Vero's share price closed up 7.5p at 180p. The latest offer represents a premium of around 43 per cent to Vero's share price on the day before it announced, in March, it was in talks which might lead to an offer.
Pentair said it expected the acquisition to be "modestly accretive" to earnings per share in 1999.
"The acquisition of Vero represents ... an excellent opportunity for Pentair to strengthen the position of its electrical and electronic enclosures group in two fast-growing segments - the data networking and telecommunications equipment markets," Pentair's chairman and chief executive, Winslow Buxton, said.
Vero would gain access to expanded distribution and marketing for its products, he said.
"We strongly believe that our offer is in the best interests of the shareholders as well as the customers of Vero and hope that our offer will be promptly recommended by the board of Vero."
Applied Power also said it was "considering its position" in the light of the Pentair bid and would make a further announcement in due course.
The rival bid from Pentair was not unexpected, but the market had been waiting to see at what price level it would be pitched, market sources said.
Pentair is a diversified industrial manufacturer based in Minnesota with a market capitalisation of $1.6bn (pounds 1bn).
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