Three European politicians say the Tanzanian government has prevented them from visiting the country to investigate the evictions of indigenous Maasai people.
The three MEPs from the Green Party, Michele Rivasi, Claude Gruffat and Pierrette Herzberger-Fofana, said that less than 24 hours before they were due to set off on Monday, they were informed that the visit had been postponed.
They said it was the third observation mission to be denied access since the end of last year.
The Maasai allege that they have been forcibly evicted from ancestral land in the north of the country.
The government says local people have moved voluntarily, under a scheme that is necessary for conservation.