Border Patrol agents have seen a "dramatic rise" in the number of African migrants detained at the U.S.-Mexico border over the past week, the U.S. Customs and Border Protection agency has said.

In a statement on Wednesday, CBP said that in the six days since May 30, more than 500 people from African countries had been arrested by Border Patrol's Del Rio Sector in Texas alone.

The agency said that had arrested a group of 34 people that same day and had previously detained a number of large groups caught trying to cross the Rio Grande River, including one group of more than 100 people.

CBP said the majority of the groups' members had been families coming from the Republic of the Congo, the Democratic Republic of the Congo (DRC) and Angola.

In addition to being the battlefield for one of the world's bloodiest civil wars, the DRC has also been hit by one of the biggest Ebola outbreaks in history, with more than 2,000 cases reported in the last 10 months.

In neighboring Angola, much of the country is still struggling to recover from the impacts of the civil war that raged across the country for 27 years after independence, leaving hundreds of thousands dead.

It is unclear what route migrants are taking from African countries. However, in recent interviews with NPR, African migrants said they had traveled from their home countries to Brazil before heading north towards the U.S.-Mexico border, a journey that would likely take several months.

In recent months, CBP has struggled keep up with the growing number of migrants and asylum seekers arriving at the U.S. border, with the majority of asylum seekers coming from Central American countries, including Guatemala, Honduras and El Salvador.

In May, a record 144,278 migrants arrived at the southern border, with more than 100,000 being families and children.

Meanwhile, agents with Del Rio's Border Patrol sector have apprehended more than 33,000 people at the border so far this year, already more than double the total number of arrests made during the previous fiscal year, according to CBP.

In a statement, Del Rio Sector Chief Patrol Agent Raul L. Ortiz said "the introduction of this new population places additional burdens on processing stations to include language and cultural differences," with the official language of both Congos being French and the official language of Angola being Portuguese.

Despite facing continued hurdles, Ortiz said his agents would "continue to meet each new challenge as the ongoing humanitarian crisis evolves."