HONG KONG, April 20 (Reuters) - Major Asian airlines have reported surging demand on European routes as travellers shun disrupted Middle Eastern hubs, in a shift analysts suggest could persist for some time even after the Iran conflict ends.

Hong Kong's Cathay Pacific Airways ( CPCAF ), Singapore Airlines, Korean Air Lines and Australia's Qantas Airways ( QUBSF ) last week disclosed robust performances on European routes in March, even as they grappled with a doubling in the price of jet fuel.

"We have ... mounted additional flights and capacity to Europe in March and April to cater for an upsurge in market demand as passengers prioritised alternative routings," Cathay Chief Customer and Commercial Officer Lavinia Lau said on Friday.

She said strong demand was expected to continue through April, fuelled by Easter travel and increased long-haul bookings that transit in Hong Kong.

Singapore Airlines said the percentage of seats filled on its European flights jumped to 93.5% in March, up from 79.7% a year earlier, due in part to spillover Europe-bound traffic as capacity through Middle East hubs fell. It was the sharpest gain for any region.

GULF CARRIER CHALLENGES

Before the conflict, Emirates, Qatar Airways and Etihad Airways together accounted for about one-third of passenger traffic between Europe and Asia and carried more than half of all passengers flying from Europe to Australia, New Zealand and Pacific Islands, according to aviation data firm Cirium.

The major Gulf carriers have been gradually restoring capacity, with all three reaching at least 60% of pre-conflict flight numbers, Flightradar24 data shows.

But they have to contend with other challenges such as Australia warning citizens not to travel to or even change planes in the Gulf, meaning they are not covered by travel insurance.

As a result, customers need to pay a premium for flights that avoid the Gulf, according to data from Google Travel.

For economy-class Sydney-London return tickets leaving next Saturday, Etihad via Abu Dhabi is the cheapest at A$1,861 ($1,333.59). Avoiding the Middle East, the most frugal one-stop options are United Airlines at A$3,144 via San Francisco and Thai Airways at A$3,901 via Bangkok.

Bank of America analysts said in a recent note that "tight pricing and share gains on Asia-Europe routes could persist for 6-12 months even after the end of the war given forward booking lags and traveler risk aversion."

ALTERNATIVE HUBS

Korean Air reported a strong European performance in its first-quarter estimated results, with operating income up 47.3% to 517 billion won ($349.38 million).

The Seoul-based carrier attributed this growth partly to "increased demand between Europe and Asia due to the Middle East war," with European passenger revenue rising 18% from a year earlier.

Looking ahead, the airline said it expects "strong transit demand" benefiting from decreased market supply from Middle East carriers.

Qantas said it had adjusted its operations to capture the shift, redeploying capacity from U.S. and domestic routes to expand flights to Paris and Rome.

"Qantas continues to see strong demand for international travel to Europe as customers seek alternative routes," the airline said.

Air traffic control manager Airservices Australia said Australia-Middle East traffic was down 77% year-on-year in March as services were rerouted via other cities.

"Asian gateways such as Singapore, Kuala Lumpur, Hong Kong, Tokyo, and Seoul are capturing much of this displaced demand and may emerge as alternative hubs and travel destinations," Airservices said.

($1 = 1,479.7600 won)

($1 = 1.3955 Australian dollars)