Tanzania has arrested three Emirati men and a Saudi national over a deadly church bombing, officials said Wednesday, clarifying earlier reports they were all from Saudi Arabia.
Five Tanzanians have also been arrested following the Sunday attack on a packed church in the northern city of Arusha that killed three people.
"There are three nationals of the United Arab Emirates and a Saudi... they were arrested while trying to cross the border" into Kenya, Arusha's governor Magesa Mulongo told AFP.
None of those arrested have been charged yet, he added.
"Investigations are continuing. They are only suspects at this time. They can be released or brought to trial, it will depend on the results of the investigations."
The bomb attack, which no group is known to have claimed yet, was described by Tanzanian President Jakaya Kikwete as "an act of terrorism" and was one of the worst such incidents to hit the east African country in years.
More than 60 people were injured when attackers hurled a bomb into the compound of the newly built Saint Joseph's Roman Catholic church.
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The church, in the Olasti district on the outskirts of Arusha, was celebrating its inaugural mass at the time and was filled with worshippers, many of whom were sitting on benches outside.
Arusha is a town popular with tourists visiting the Serengeti national park and snowcapped Mount Kilimanjaro.
The Vatican's ambassador to Tanzania, Archbishop Francisco Montecillo Padilla, was among those attending mass at the church but was not harmed.
Officials have given no indication as to who might have carried out the attack, but tensions have been high between Tanzania's Christian and Muslim communities in recent months.
Kikwete, who said he was "shocked and deeply saddened" by the incident, has called on people to remain calm while police investigate the attack.
Around half of Tanzanians are believed to be Christian, and around a third Muslim, although there are no official figures.
In neighbouring Kenya -- whose troops invaded southern Somalia in 2011, prompting warnings of revenge by the Al-Qaeda linked Shebab insurgents -- several churches have been targeted in attacks similar to the Arusha blast.
While Tanzania does not have troops in Somalia, it is home to Islamist groups connected to radical groups in the wider region including the Shebab, according to United Nations experts.