Sir

We would like to make it clear (see Opinion, Nature 417, 1; 2002) that in our petition we are calling not for a boycott of individual scientists in Israel but for a suspension of institutional links until Israel complies with UN resolutions and begins to negotiate seriously with its Arab neighbours along the lines of the Saudi and other similar peace plans.

You argue that such sanctions are ineffective and that Mr Sharon will lose no sleep over them. Nevertheless, the peaceful boycott by the world's academic and cultural communities was instrumental in ending apartheid in South Africa.

If to make our demand is to be partisan, so be it — peace and justice demand partisanship. Israeli researchers may well find this prospect unpalatable, but some in Israel have selflessly given their support. Many of the signatories of our letter are receiving torrents of hate e-mail, especially if they are Jewish, being accused of everything from anti-semitism to support for terrorism. Such allegations conflate uncritical support for the Israeli state with Jewish identity, and are both repugnant and unjust.

Finally, we would like to point out that all authors of our petition signed in their personal capacity; institutional affiliations were given for identification purposes only.