Tunisian security forces have arrested three suspected militants after uncovering their links to Anis Amri, the Tunisian national believed responsible for the Berlin Christmas market attack that killed 12 people.
Amri's nephew was among the three men and had been in touch by social media messaging with Amri, the interior ministry said.
Amri, 24, was killed yesterday by Italian police after he pulled a gun on them during a routine search. He is suspected of driving a truck through the busy Berlin market on Monday, also injuring 48 others.
In a video released yesterday after his death, he is seen pledging his allegiance to militant group Islamic State leader Abu Bakr al-Baghdadi.
The three arrested were between the ages of 18 and 27 and had been active around Amri's hometown of Oueslatia, central Tunisia.
The nephew had been communicating with Amri about declaring allegiance to the so-called Islamic State and had also sent him money using a false name, it said.
Separately in Tunisia, hundreds of people gathered outside Tunisia's parliament to protest against letting jihadists who fought overseas to return to the country.
More than 5,000 Tunisians are fighting for jihadist groups abroad, mainly in Iraq, Syria or neighbouring Libya, according to a UN working group on mercenaries.
Yesterday, the country's Interior Minister Hedi Majdoub told parliament 800 Tunisian nationals who had fought for extremist groups abroad had since returned to the country.
Since its 2011 revolution Tunisia has faced repeated jihadist attacks, killing more than 100 soldiers and policemen, as well as about 20 civilians and 59 foreign tourists, according to official figures.
Security forces remain 'vigilant' after Berlin attack - Kenny
The Taoiseach has written to German Chancellor Angela Merkel to express sympathy over the Berlin attack and said security forces in Ireland remained vigilant.
Asked whether Ireland could be similarly targeted, Enda Kenny said bigger security and police forces in other countries had failed to prevent the likes of the Berlin atrocity or the almost identical attack on Bastille Day in Nice, France.
"You can never rule anything out," he said.
"But we like to think that in this country people are vigilant, that we are careful and we will do everything we can to protect our citizens."
The Taoiseach added: "I would hope that nothing like that will happen here."
Mr Kenny said gardaí and Defence Forces are making every effort possible "to see that we are protected and that lives are protected in that regard".
Separately, he rejected calls from an imam to regulate Irish mosques in an attempt to thwart Muslims here being radicalised.
Shaykh Dr Umar Al-Qadri, chairman of the Irish Muslim Peace and Integration Council, was reported as saying the Government should set up a Muslim council to regulate how mosques are being run and the education they are providing.
However, Mr Kenny said Ireland enjoys freedom of religion and religious practices and he did not agree with the suggestion.
"Obviously, we respect the right of every religion to preach to its own followers and we expected that preaching to be in accordance with peaceful means and the religious beliefs that people have," he added.
