The brother of a Syrian ISIS bomb plotter found hanged in a German jail has vowed to come to Europe as a refugee to avenge his sibling.

Terror suspect Jaber al-Bakr killed himself in his prison cell after three fellow Syrians he met in Leipzig handed the 22-year-old over to police.

In an interview, his brother Alaa al-Bakr issued a warning to the three men, telling a German newspaper: 'My reaction as an Arab is revenge.'

The brother of Syrian ISIS bomb plotter Jaber al-Bakr (pictured) who was found hanged in a German jail has vowed to come to Europe as a refugee to avenge his sibling

In an interview, Alaa al-Bakr issued a warning to the Syrian refugees who turned his brother Jaber over to police, telling a German newspaper: 'My reaction as an Arab is revenge'

When asked to explain what he meant by the remark, he told Die Welt: 'You understand. I have nothing more to say about it. I will come as a refugee.'

Al-Bakr said his brother had been in Syria two months before his arrest with a group of Islamists.

The suspect, Jaber al-Bakr, arrived in Germany from Syria in 2015 and gained refugee status, but returned to Syria earlier this year, his brother told the German daily.

'The last time that we spoke was two months ago, he was in Idlib (northwest Syria). He told me then that he was very angry and sad because of the war,' he told the paper from his house in the Damascus region.

He said his brother, 22, was involved in 'humanitarian aid' with the hardline Islamist Ahrar al-Sham rebel group in Syria, a rival to ISIS.

Jaber al-Bakr was arrested in the city of Leipzig late on Sunday after a manhunt that began some 48 hours earlier when police raided his apartment and found explosives

Jaber al-Bakr may have joined ISIS, although he believed the group 'did not represent Islam,' Alaa al-Bakr said.

He said his brother was radicalised in Germany and may have been influenced by a Muslim leader or a mosque in Berlin or near Berlin.

He also told Die Welt he did not believe his brother's death was suicide.

'I'm sure it was the police who killed him,' he claimed.

Jaber al-Bakr was arrested in the city of Leipzig late last Sunday after a manhunt that began some 48 hours earlier when police raided his apartment and found explosives.

But on Wednesday he was found hanged in his cell after an apparent suicide.

The death sparked cries of outrage and concern that Germany may never learn the plans for an attack he was suspected of planning against a Berlin airport.