By Robert Walker
In Rwanda's capital, Kigali, new restrictions have been introduced on those wanting to come to the city from rural areas.
Genocide suspects are believed to be trying to avoid trial at village courts
Those without a fixed address in the capital will have to go back to their own districts to get documents showing they are not guilty of any crimes.
The move comes after Rwanda has stepped up security against potential infiltration by Hutu rebels.
But the city council is denying speculation this is an additional security measure to weed out potential rebel infiltrators.
The restrictions introduced by Kigali city council have been billed as a measure to improve security in the city.
Kigali's Vice Mayor Gaston Rusiha told the BBC the move was a response to the growing influx of job seekers from rural areas.
From now on those without a fixed address in Kigali will have to return to their home districts - to get certificates of good character from local authorities. This is in addition to the ID cards citizens must already carry.
Those who fail to obtain these documents will be subject to round ups by police.
Vice Mayor Rusiha said the exercise was intended to make it easier to identify robbers and those seeking to avoid Gacaca trials.
After a pilot phase, the Gacaca village based courts - which try lower order genocide suspects - are now due to start across the country.
Mr Rusiha said as a result some suspects were seeking refuge in Kigali.
Attacks on Congolese army bases have intensified recently
There has been speculation that the new restrictions on movement into the capital are aimed at identifying rebel infiltrators.
Last month the Rwandan army said it repulsed an incursion by Hutu rebels from neighbouring Congo.
And security has been stepped up on Rwanda's borders.
But Vice Mayor Rusiha denied this was the reason - he said there had been no cases of infiltration into the city.
However, there are concerns about the effect the measures will have on the poorest residents of the capital.
A chronic shortage of land in Rwanda forces many into cities and towns in search of informal jobs.
This is the latest in a series of controversial measures introduced by the city council - including bans on late night drinking on weekdays, the forced round up of street children and restrictions on hawkers.