17 August 1970
On 17 August 1970, two top South African scientists were refused entry into the Soviet Union during the International Science Congress in Leningrad. The scientists were Prof. L.H. Wells, Head of the Department of Anatomy at the University of Cape Town and Prof. Phillip Tobias, a palaeontologist at Wits University and initiator of the excavation at Sterkfonetin in 1966. Both Prof. Wells and Tobias were invited to speak at the Ninth International Science Congress, but the Russians refused their visas at the last moment. Prof. Wells said he thought that the refusal was due to pressure on the Russian authorities from Afro-Asians. Prof. Tobias had, on previous occasions, attended the Congress, but it would have been Prof. Wells’ first attendance.
References

The Cape Times, 18 August, 1970. ‘Russians Bar two SA Scientists’ in The Cape Times, Available at: The National Library of South Africa, Cape Town Campus|CradleofHumankind.co.za, N.D, ‘Tobias, Phillip’ [online], Available at: www.cradleofhumankind.co.za [Accessed 05 July 2011]