I always look forward to an issue of the English "New Scientist" magazine. The current issue, Volume 206, number 2767, pp26-27 was no exception.
SETI researcher Seth Shostak writes:
"Stephen Hawking is worried about aliens. The famous physicist recently suggested that we should be wary of contact with extraterrestrials, citing what happened to native Americans when Europeans landed on their shores...For three years, this issue has been exercising a group of SETI scientists in the International Academy of Astronautics...In truth, banning broadcasts would be impractical...such considerations motivated the SETI group...to reject a proscription of transmission to the sky..."