Police on Sunday arrested 29 men in Dandora phase 5 believed to be from Ethiopia and who are in the country illegally.
The suspects were taken to Dandora police station and later transferred to Buruburu police station.
According to police, the men did not have documents to show they were legally in Kenya.
Journalists who went to cover the arrests and transfer of the immigrants were met by firm objection from the police.
Police barred anyone from filming anything, not even getting footage of the alleged aliens in transit.
The arrest comes as the government remains keen on rooting out illegal immigrants in the country.