The Mexican attorney general's office says it is setting up a unit to investigate the murders of women in the northern city of Ciudad Juarez.
The UN has criticised Mexico's handling of the Juarez murders
The team will start work by widening existing inquiries into 22 cases that occurred in the past two years.
It is not clear whether the unit will look into the deaths of the other 300 women killed in the city since 1993.
The move comes a day after Amnesty International said that the government was not doing enough to investigate.
Rights groups say local investigators have either botched their inquiries or obstructed efforts to secure justice.
There have been several arrests, but the killings have continued.
Two girls aged seven and 10 were murdered earlier this month.
The killings were first exposed when bodies were found in desert graves and by city roadsides in 1993.
The murders have been variously attributed to serial killers, drug cartels and domestic violence.
Some of the killings are believed to have been sexually motivated.
Many of the victims were poor working mothers employed in factories in the industrial city on the border with Texas.
Earlier this year the government announced a $2.7m compensation fund for relatives of the victims.
Families say the crimes have never been properly explained.
The UN has also criticised Mexico's handling of violence against women.