WASHINGTON/ DUBAI (AFP) � More than 20 countries have joined the US-led coalition to protect Red Sea shipping from attacks by Yemen's Houthi rebels, the Pentagon said on Thursday.

The Iran-backed Houthis have repeatedly targeted vessels in the vital shipping lane with strikes they say are in support of Palestinians in Gaza, where Israel is battling militant group Hamas.

"We've had over 20 nations now sign on to participate" in the coalition, Pentagon spokesman Major General Pat Ryder told journalists.

Ryder said the Huthis are "attacking the economic well-being and prosperity of nations around the world", effectively becoming "bandits along the international highway that is the Red Sea".

Coalition forces will �serve as a highway patrol of sorts, patrolling the Red Sea and the Gulf of Aden to respond to, and assist as necessary, commercial vessels that are transiting this vital international waterway,� he said, calling on the Houthis to cease their attacks.

Vowing to destroy Hamas, Israel began a relentless bombardment of targets in Gaza, alongside a ground invasion, which Gaza�s Hamas government on Wednesday said has killed at least 20,000 people.

Those deaths have provoked widespread anger in the Middle East and provided an impetus for attacks by armed groups in the region, including the Houthi strikes on Red Sea shipping.

The United States announced the multinational Red Sea coalition on Monday, while the Houthis warned two days later that they would strike back if attacked.

Meanwhile, a drone strike damaged a ship off the coast of India on Saturday but caused no casualties, two maritime agencies said, with one reporting the merchant vessel was linked to Israel.

The attack caused a fire on board, according to the British military�s United Kingdom Maritime Trade Operations, or UKMTO.

Ambrey, a maritime security firm, said the �Liberia-flagged chemical/products tanker... was Israel-affiliated� and had been on its way from Saudi Arabia to India.

Both agencies said the attack occurred 200 nautical miles southwest of Veraval, India.

The Indian navy said it had responded to a request for assistance.

�An aircraft was dispatched and it reached overhead the vessel and established safety of the involved ship and its crew,� a navy official told AFP.

�An Indian navy warship has also been dispatched so as to provide assistance as required.�

There was no immediate claim of responsibility for the strike which came amid a flurry of drone and missile attacks by Yemen�s Iran-backed Houthi rebels on a vital shipping lane in the Red Sea.

Last month, an Israeli-owned cargo ship was hit in a suspected drone attack by Iran�s Islamic Revolutionary Guard Corps in the Indian Ocean, according to a US official.

The Malta-flagged vessel managed by an Israeli-affiliated company was reportedly damaged when the unmanned aerial vehicle exploded close to it, according to Ambrey.

The Houthi rebels have launched more than 100 drone and missile attacks, targeting 10 merchant vessels involving more than 35 different countries, according to the Pentagon.