Offer Update

28 April 2005

Not for release, publication or distribution in, into or from Australia,
Canada, Japan or the United States

                             Recommended Offer by                              

                                  UBS Limited                                  

                                 on behalf of                                  

                                 Microgen plc                                  

                                      for                                      

                          AttentiV Systems Group plc                           

                      Additional Irrevocable Undertaking                       

Further to the announcement released earlier today by Microgen plc ('Microgen')
regarding its agreed terms of a recommended offer for the entire issued and to
be issued share capital of AttentiV Systems Group plc ('AttentiV') ('Offer'),
Microgen announces that it has since received an irrevocable undertaking from
Gartmore Investment Limited ('Gartmore') to accept the Offer in respect of
1,535,628 AttentiV shares held by Gartmore, representing approximately 2.5 per
cent. of AttentiV's existing issued share capital. The irrevocable undertaking
provided by Gartmore will cease to be binding only in the event of an
announcement of a third party offer representing at least a 10 per cent.
premium to the value of the Offer.

Microgen has now received irrevocable undertakings from AttentiV shareholders
to accept (or use all reasonable endeavours to procure the acceptance of) the
Offer in respect of 21,935,757 AttentiV shares, representing approximately 36.2
per cent. of AttentiV's existing issued share capital.

In addition to the irrevocable undertakings, Microgen has received non-binding
letters of intent to accept the Offer in respect of a total of 9,663,475
AttentiV shares representing approximately 16.0 per cent. of the existing
issued share capital of Microgen.

In aggregate, therefore, Microgen has received irrevocable undertakings and
non-binding letters of intent to accept the Offer in respect of 31,599,232
AttentiV shares, representing approximately 52.2 per cent. of the existing
issued AttentiV shares.

Enquiries:

UBS Investment Bank (Financial Adviser to Microgen)

John Woolland

Nick Adams

020 7567 8000

Financial Dynamics (PR Adviser to Microgen)

Giles Sanderson

Ben Way

020 7831 3113

Hawkpoint (Financial Adviser to AttentiV)

Paul Baines

Graham Paton

020 7665 4500

UBS Investment Bank is acting exclusively for Microgen in connection with the
Offer and no one else and will not be responsible to anyone other than Microgen
for providing the protections afforded to clients of UBS Investment Bank or for
providing advice in relation to the Offer.

Hawkpoint, which is authorised and regulated in the United Kingdom by the
Financial Services Authority, is acting exclusively as financial adviser to
AttentiV in connection with the Offer and no one else and will not be
responsible to anyone other than AttentiV for providing the protections
afforded to clients of Hawkpoint nor for providing advice in relation to the
Offer.

This announcement does not constitute an offer or invitation to purchase or
subscribe for securities.