Two home-made bombs exploded in Yemen's southern port of Aden on Sunday, injuring two people, police said.
Yemen, which is fighting a resurgent wing of al Qaeda at home, is also facing growing separatist unrest in its south.
The devices went off outside a bank and in a park, where two people were wounded, a police official told Reuters.
Police cordoned off the areas near the blasts, residents said.
The impoverished Arabian Peninsula country has been the focus of Western security concerns following a string of attacks attributed to a Yemen-based arm of al Qaeda, including an attempted bombing of a U.S.-bound plane in December and a suicide attack targeting the British ambassador in April.
North and south Yemen formally united in 1990 but many in the south, where most of Yemen's oil facilities are located, complain that northerners exploit the south's resources and discriminate against southern citizens. Officials deny the allegations.