Mr Twagiramungu will run as an independent presidential candidate
Former Rwandan Prime Minister Faustin Twagiramungu, is on his way home after eight years in exile in Belgium.
He has been living in Belgium since 1995, a year after the genocide in Rwanda.
He expected a "very sad homecoming", he told the BBC's Network Africa while in London on his way to Rwanda from Brussels.
He announced last week that he will stand in the country's presidential election due later this year.
Presidential and parliamentary elections, set for September, were announced after Rwandans voted overwhelmingly in a referendum last month to approve a draft constitution.
"It is not that they hate me - they are very scared"
Former Rwandan Prime Minister
The constitution sets out the legal basis for the polls by lifting a suspension on political activity and prohibiting parties from identifying themselves along ethnic lines.
The ban aims to prevent the kind of extremism that led to Rwanda's genocide in 1994, when up to a million people were killed in a government-orchestrated campaign aimed at ridding the country of its Tutsi minority.
Many Hutus were also killed either in reprisal attacks or because they refused to go along with the genocide.
Mr Twagiramungu, a moderate Hutu, was prime minister of Rwanda's post-genocide government of national unity before he was sacked in 1995.
He is hoping to contest the elections as an independent candidate because in May, the Rwandan parliament voted to dissolve his party, the Democratic Republican Movement.
Most of Mr Twagiramungu's family were killed nine years ago
He said he will be staying in a hotel when he got to Rwanda, and he had not been given any guarantee for his safety by the authorities.
No safety guarantees from Mr Kagame's government
"I have no alternative at all because my house has been destroyed and the other one is in the hands of the bank, so I have decided to stay in a hotel", he explained.
The former prime minister said that some of his relatives and close friends in Rwanda had asked him not to contact them .
"It is not that they hate me. They are very scared and they do not want to be known to be organising something for an opposition leader who is coming back home," he said.
However he said he was very optimistic that he "will win the elections, despite all the difficulties lying ahead".
Mr Twagiramungu has already informed the Rwanda government through the embassy in Brussels that he was going back and that he wanted to maintain "good relations with the authorities" in Kigali.
In 1998 he accused the then Tutsi-led RPF government, from which he was forced to resign, that it was equally guilty of genocide.
He told a French parliamentary commission investigating France's role during the genocide, that the RPF government, had killed civilians, and was continuing to kill them in the north-west of Rwanda, on the pretext of ending a Hutu rebel insurgency.