AP

A jailed activist on a hunger strike since early February is in "good health" and receiving medical care, Bahraini officials said on Wednesday, responding to opposition groups claiming his condition was sharply deteriorating.

The statement by Bahrain's Interior Ministry came after social media postings raised alarms about the fate of Abdulhadi al-Khawaja, who has been on hunger strike since February 8.

Al-Khawaja, 51, and seven other Shi'ite activists were sentenced to life in prison last year. The convictions were part of Bahrain's crackdown during the 14-month-old uprising by the country's Shi'ite majority, which seeks to reduce the wide-ranging powers of the ruling Sunni dynasty.

The Interior Ministry statement described al-Khawaja as "is in good health, despite rumours" and added that "he is in hospital, receiving full medical care."

On Monday, an appeals court delayed a decision until at least April 30 on efforts by al-Khawaja and others to challenge their convictions, which were issued by a military-led court.

Earlier this month, Bahrain rejected Denmark's request to take custody of al-Khawaja, who is also a Danish citizen. On Monday, Danish Foreign Minister Villy Soevndal called the situation "very, very serious."

Al-Khawaja has become a powerful rallying point for near daily protests in the strategic kingdom, which is home to the US Navy's 5th Fleet.

In the latest violence, Bahraini authorities said an explosion wounded four police officers during clashes late on Tuesday in one of the anti-government strongholds. At least 50 people have been killed in unrest since February 2011.

In Washington, the US State Department issued an updated travel alert for Bahrain, warning of "spontaneous and at times violent anti-government demonstrations" that can include firebombs by protesters and the use of tear gas, stun grenades and birdshot by security forces.

The statement urged Americans to avoid all demonstrations, "as even peaceful ones can become unruly." It did not call on US citizens to leave.