Tanzania has expelled hundreds of Burundian refugees - many of them married to Tanzanians
The Red Cross in north-eastern Burundi said it had received more than 600 Burundians last week.
It said some of them had been living in Tanzania for more than 30 years and had families living there.
The United Nations says more than 1,700 Burundian refugees have been deported this year. Some 200,000 Burundians are live in UN refugee camps in Tanzania.
Muyinga Province governor Mohamed Feruzi told AFP news agency that many arriving at the border were married and their belongings were still in Tanzania.
"Tanzania separates families, we have examples of men and women who are married to Tanzanians who were thrown out, while their husbands, women and children remained in the country," he said.
The Tanzanian authorities have not commented.
Burundi is emerging from a civil war that has claimed some 300,000 lives.
Tanzania kicks out Burundians