Complex sentence: Uzbekistan's Ministry of Labor does not publish information on Uzbek citizens working abroad, but Russia's Federal Migration Service reports 2.5 million Uzbek migrant workers in Russia and there are indications of up to 1 million Uzbek migrants working illegally in Kazakhstan.
Split into simpler sentences: Uzbekistan's Ministry of Labor does not publish information on Uzbek citizens working abroad, but Russia's Federal Migration Service reports 2.5 million Uzbek migrant workers in Russia. There are also indications of up to 1 million Uzbek migrants working illegally in Kazakhstan.