(Updates with Sea Champion cargo in paragraphs 3-4; CENTCOM comment, 19-20)

LONDON/ADEN/ATHENS, Feb 20 (Reuters) - The Greek-flagged bulk cargo vessel Sea Champion arrived in the southern Yemeni port of Aden on Tuesday after being attacked in the Red Sea in what appeared to have been a mistaken missile strike by Houthi militia, shipping and military sources said.

Shipping risks are escalating due to repeated drone and missile strikes in the Red Sea and Bab al-Mandab Strait by the Iran-aligned Houthis since November. U.S. and British forces have responded with several strikes on Houthi facilities but have so far failed to halt the attacks.

The Sea Champion, which was ferrying corn from Argentina to Aden, the seat of Yemen's internationally recognised government, was attacked twice on Monday, with a window damaged but no crew injuries, Greek shipping ministry sources said.

A port source in Aden and a separate shipping source said the vessel was unloading part of its cargo of some 9,229 tonnes of corn in Aden, before it heads to the northern Yemeni port of Hodeidah, an area controlled by the Houthis, where it was meant to discharge the remaining load of some 31,000 tonnes.

The port source in Aden, who declined to be identified, said the attack on the vessel was a mistake. A separate port source in Hodeidah, who also declined to be identified, said the Houthis informed them that the attack was not intentional.

Houthi officials could not be immediately reached for comment.

The vessel's Athens-based operator Mega Shipping and Greek shipping ministry officials declined to comment on the vessel's arrival.

The Sea Champion was anchored in Aden port with its last position updated at 1211 GMT, according to data from ship tracking and maritime analytics provider MarineTraffic.

The Houthis, who control Yemen's most populous regions, have attacked vessels with commercial ties to the United States, Britain and Israel, shipping and insurance sources say.

CONCERNS GROW OVER RUBYMAR

Despite retaliatory Western attacks on them in Yemen, the Houthis have vowed to continue striking ships linked to Israel in solidarity with Palestinians until Israeli forces stop their war in the Gaza Strip.

Shipping sources said the Sea Champion, which had made grain deliveries in the past to Yemen, had U.S. ownership links.

So far, no ships have been sunk nor crew killed from the Houthi attacks in a sea lane accounting for about 12% of global maritime traffic.

Nonetheless, concerns were mounting over the fate of the Rubymar ship, which was hit by missiles in the Gulf of Aden on Sunday, despite the crew evacuating onto another vessel.

In a maritime advisory seen by Reuters, commercial ships were cautioned to stay away from the area of the abandoned vessel amid fears it might sink.

A U.S. defense official said the vessel had not sunk.

Stephen Cotton, General Secretary of the International Transport Workers' Federation (ITF), the leading union organisation for seafarers, said the Rubymar attack should be a wake-up call "to immediately prioritise seafarers' safety, before we see human lives lost on the Red Sea".

He said an immediate, permanent ceasefire in the war between Israel and Gaza's ruling Palestinian Islamist group Hamas was a critical step towards guaranteeing safe transit through the Red Sea.

There was also alarm that commercial ships could face new perils including the possibility of sea mines being deployed, maritime security sources said.

The U.S. military's Central Command conducted strikes on various targets on Monday and Tuesday, including what was believed to be the first unmanned underwater vessel (UUV) used since Houthi attacks began.

"These actions will protect navigational rights and freedoms and make international waters safer," CENTCOM said.

While many ships are diverting around southern Africa to avoid the Red Sea, some have continued to sail through.

French container shipping group CMA CGM said on Tuesday its Jules Verne vessel had transited the Red Sea under French naval escort, after suspending crossings for security risks earlier this month.

The European Union on Monday launched a naval mission to the Red Sea to "safeguard freedom of navigation" there amid hopes of more protection and support for commercial shipping.

France has provided navy escorts in recent weeks for some shipping traffic including French-linked vessels.

(Reporting by Jonathan Saul in London, Mohammed Ghobari and Reyam Mukhashaf in Aden, Renee Maltezou in Athens and Maha El Dahan in Dubai, and Lisa Baertlein in Los Angeles; editing by William Maclean and Mark Heinrich)