A third small bomb has exploded in the central square of Palma de Majorca in Spain.
Earlier another bomb exploded in a restaurant in Palma, while a device was reportedly detonated by Spanish authorities in a hotel.
The explosions followed a telephone warning.
Some small damage was reported in the attacks, authorities said, but there are no reports of injuries.
ETA, which has been waging a violent campaign for Basque independence, has claimed responsibility.
ETA earlier issued a statement claiming responsibility for several recent attacks.
In the statement which was released to the Basque daily Gara, the group claimed the 19 June car bomb attack that killed 49-year-old police inspector Eduardo Puelles Garcia in the Basque town of Arrigorriaga.
The statement also claimed the 30 July car bomb attack outside a police barracks on the Mediterranean island of Majorca that killed two members of the Civil Guards paramilitary police, Diego Salva and Carlos Saenz de Tejada.
The group also claimed a car bomb attack on a Civil Guards barracks in the northern city of Burgos on 29 July that injured 40 people, and a bomb attack on the offices of the ruling Socialist Party in the Basque town of Durango on 10 July in which no one was injured.
Founded half a century ago, ETA is blamed for the deaths of 828 people in its violent campaign for an independent Basque homeland encompassing parts of northern Spain and southwest France.
Despite claiming the attacks ETA said it 'does not seek to impose any project, unlike successive Spanish leaders. It is ETA which has over the long decades sought dialogue and political solution.'
The group resumed its campaign of violence in mid-2007 after a 15-month ceasefire for ultimately unsuccessful talks the with government of Prime Minister José Luis Rodríguez Zapatero.
It is considered a terrorist organisation by the EU and the US.