The UN's refugee agency says it was seriously concerned about Israeli proposals to relocate tens of thousands of Eritrean and Sudanese asylum seekers and refugees to third countries in Africa.

If they don't comply, Israel says they would face imprisonment.

For nearly a decade, Israel has struggled to deal with tens of thousands of non-Jewish Africans entering the country, seeking asylum or work.

But human rights activists say Israel's plans violate international and Israeli laws.

Asylum seekers

Mr Adi Dori Avraham from Israeli refugee rights group Assaf, said the relocation of the refugees from Israel was not an entirely new phenomenon.

"This has been going on for the last few years. Under secret agreements, they transfer asylum seekers to countries like Uganda and Rwanda," he told BBC Focus on Africa.

"When these people arrive, they are given no protection, no documents.

"What happens is they are just pushed to continue a journey north towards Europe... which is known to be extremely dangerous."

Would pay

Israel's government has previously said that it would pay the Rwandan government $5,000 for every African asylum seeker it accepts from Israel.

Seven leading Israeli human rights organisations appealed to Rwandan President Paul Kagame not to accept refugees sent from Israel.

Israeli Prime Minister Benjamin Netanyahu has announced the opening of a new Israeli embassy in Rwanda.