All 18 Indians who were among the 22 crew members on board a Mumbai-bound ship hijacked and taken to Somalia are safe, according to the chief of the company owning the vessel.

Fredi Stolzenberg, chief of Stolt Shipping, said no ransom demand has been made yet. The crew also included one Russian, two Filipinos and one Bangladeshi.

The chemical tanker Stolt Valor, which bears a Hong Kong flag and carrying over 23,000 tonnes of oil products, is reported to have been hijacked in the Gulf of Aden on Tuesday at around 1315 hours, according to officials in the Directorate General of Shipping in Mumbai.

The Gulf of Aden is near Somalia's dangerous waters and the Hong Kong vessel is reported to be the 12th to be hijacked in the pirate-infested waterway since July 20. The ship was seized in the same place where other vessels met the same fate, officials said.

The vessel's last port of call was Suez after which it was supposed to arrive here, officials said, adding that the vessel was commandeered to Somalia.

"We know that the Indians are safe. All the crew on board are also safe," said Stolzenberg.

"We have not spoken to the hijackers today. They have let some of the crew call the company. They said all the crew are safe on board. We had some communication yesterday. We cannot call them they can only call us. It is not up to us to do anything. We have to wait. But what we don't want is to do anything that risks the safety of the crew," he said.

Pirates have stepped up attacks on merchant vessels in the recent months in the Gulf of Aden, an important  waterway for shipping.