By Farah Master

HONG KONG, Nov 3 (Reuters) - October is set to be the worst month on record for casino revenues in the world's biggest gambling hub Macau as China's pervasive war on corruption, combined with fewer tourists and slowing economic growth, dampen the appetite to wager.

Gambling revenues for the month are expected to have fallen some 20-23 percent year-on-year, analysts say, the sharpest drop since the former Portuguese colony started keeping records.

October would also be the fifth consecutive month of declines after two years of rapid growth which saw Macau surpass Las Vegas in revenue by seven times. The special administrative region is the only place where casino gambling is legal in China, and the Macau government is due to report the October revenue figures on Monday.

"It is worse in October than it was before October," Steve Wynn, chief executive of Wynn Macau Ltd, told a recent earnings call. The casino operator is building a $4 billion integrated resort, complete with a lake and air-conditioned gondolas, in the territory.

"I don't know if it is a squall or if we are in the rainy season, or how long it will last, but we are still very bullish on Macau," the gaming magnate added.

Casino revenues make up about 80 percent of Macau's income.

Beijing's two-year anti-corruption campaign has taken its toll on the gaming sector, keeping big-spending, wealthy gamblers away - data from Macau's gaming and inspection bureau shows that VIP revenue accounted for a record low 56 percent of total revenues in the third quarter.

A slew of factors over the past six months have also cut the number of so-called "mass market" gamers from the mainland.

Many small-time gamblers combine visits to Macau with Hong Kong, which is an hour away by high-speed ferry. Tourist numbers have fallen after China restricted access to Hong Kong due to pro-democracy protests in the city. Tighter visa regulations by the Macau government have also shortened the number of days visitors can stay.

Macau government curbs on the popular UnionPay credit card, which gamers widely used to circumvent China's strict currency regulations, have also curtailed gambling spend, as have the tight credit conditions and falling housing prices in the mainland, where economic growth is slowing.

Casino operators are also waiting to see the impact of a ban on smoking in casino floors, which began in October.

Hong Kong listed gaming shares have fallen between 20-38 percent since the start of the year, substantially underperforming the benchmark Hang Seng Index which is up 2 percent in the same period, and highlighting investors concerns about Macau's gambling prospects.