VW’s chief executive Bernd Pischetsrieder told the Financial Times Deutschland that even if the bid, worth €9.6 billion, was improved it would still be unacceptable.
In Stockholm the price of shares in Scania fell by 5.81 percent to 430 kronor in initial trading. The bid is widely regarded as blocked if Volkswagen is hostile.
Pischetsrieder said that MAN should abandon its approach in favour of private talks.
MAN, a German industrial group, had said on September 19 that it would be happy to have Volkswagen as a shareholder if its bid succeeded.
Pischetsrieder said however that he was in favour in principle of combining Scania and MAN with VW’s heavy truck business in Brazil.
But he added: “For me this can’t be achieved by a takeover of Scania by MAN. I have rejected the bid and have no intention of changing my mind.”
He also objected to the terms because they put the same price on different classes of shares in Scania.
Pischetsrieder said he had repeatedly told MAN chief Hakan Samuelsson that he would not approve a takeover.
Samuelsson has said MAN is preparing an improved offer, but VW’s support is vital because it controls 34.32 percent of Scania’s voting rights and 18.7 percent of its capital.
Pischetsrieder also complained that the offer undervalued VW’s share in Scania. VW mainly holds A shares in Scania which carry greater voting rights, but MAN is offering the same price for A and B shares, valuing each Scania share at 442 kronor.
MAN currently ranks third among European truck makers.