EU's anti-piracy naval force have said pirates were holding a total of 31 vessels and 688 hostages [AFP]

A family of five including three children aged 13, 15 and 17 have been kidnapped by Somali pirates, officials have confirmed.

The group, all from Denmark, were sailing their boat around the Indian Ocean when they were taken hostage along with two members of their crew.

The pirates have now warned that they will kill the hostages if any rescue attempt is made.

Danish naval command received a distress signal from the vessel on February 24, the country's foreign ministry said on Tuesday.

"It can now be confirmed that the sailboat has been hijacked by pirates in the Indian Ocean," the ministry said.

Condemnation

Meanwhile, the Associated Press spoke to Abdullahi Mohamed, who reportedly has ties with the gang holding the Danish family.

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Mohamed told the AP on Tuesday that any attack against the pirates would result in the deaths of the hostages. He referred to the killings last week of four American hostages taken captive by pirates on their yacht.

Mohamed "has provided reliable information to AP in the past," the news agency said.

The Danish ministry confirmed that the family - parents and their three children - and two Danish crew members were aboard when the vessel was seized.

"It's almost unbearable to know that children are involved, and I vigorously condemn the pirates," Lene Espersen, the Danish foreign minister said.

She added that the Danish government would do "everything in their power" to help the hostages.

No negotiation

However, the foreign minister said that the country's government "does not negotiate with pirates".

The family had left on a two-year around the world tour expected to end in mid-2011, a neighbour told a Danish tabloid.

Just a week ago, four Americans were found dead on a hijacked yacht in the Arabian Sea as US forces tried to negotiate an end to a hostage drama involving Somali pirates.

The US military said a firefight left two pirates dead and 13 more captured.

Among the Americans killed were Jean and Scott Adam, a retired couple active in missionary work who had been sailing the world on the for more than seven years and had planned to take in sites from India to Djibouti to Crete on their latest trip.

US military officials blamed the band of 19 pirates who commandeered the yacht in waters southeast of Oman for the Americans' deaths.

The sequence of events was not immediately clear, but the US military's Central Command said the dead hostages were only discovered after US forces responded to gunfire and boarded the pirated yacht.

Piracy is endemic off the Horn of Africa though pirates have traditionally target cargo vessels and not private craft.

As of last week, the EU's anti-piracy naval force said pirates were holding a total of 31 vessels and 688 hostages.

Source: Agencies