Two police officers have been slightly injured in an explosion in the centre of Kyrgyzstan's capital, Bishkek, ahead of a visit by US Secretary of State Hillary Clinton.
The blast came a day after security forces battled Islamic militants in a restive southern city.
Security officials said the attacks appear to be part of systemic attempt to foment turbulence in the Central Asian nation by means of an Islamist-inspired terror campaign.
Authorities said the explosion took place outside the venue of a high-profile trial against top officials of the recently deposed government. The blast, which formed a deep crater in the road, was set off outside an entrance used by defendants in the trial. The Health Ministry said two police officers suffered minor injuries.
Mrs Clinton is due to travel to the country on Thursday. Her visit comes amid US attempts to buttress stability in the troubled former Soviet nation, which hosts a key air transit facility used as a jumping-off point for troops travelling to and from nearby Afghanistan.
Tensions are high in the country amid sensitive political bargaining over the formation of a new government and renewed violence in the restive south.
Clashes between security forces and Islamic militants broke out on Monday in the city of Osh. Officials said the militants were planning a series of terrorist attacks in the country. Three insurgents were shot and killed by government forces during the gun battle, while another militant blew himself up.
Security Council secretary Marat Imankulov said three suspects detained after the battle were members of the Islamic Movement of Turkestan.
Kolbay Musayev, deputy chairman of the National Security Service, said the militants had selected 33 targets for terrorist attacks, including eight in the capital. "Thanks to active efforts of law enforcement and intelligence agencies, their plans were defeated," he added.
A Kyrgyz court is hearing the case against 28 former officials, including the self-exiled former President Kurmanbek Bakiyev, on charges that they were complicit in ordering troops to open fire on demonstrators during protests in April which brought down the government.