* Q1 op profit fell 5.4 pct to 53.32 bln yen
* Analysts had estimated op profit of 51.24 bln yen
* Global vehicles sales up 16 pct with China, US boost
* Shares up more than 5 pct; China outlook uncertain (Adds exec comment, details on China)
By Minami Funakoshi
TOKYO, July 30 (Reuters) - Japan's Mazda Motor Corp said quarterly profit fell 5.4 percent, but still beat estimates as higher auto sales in China and the United States cushioned the blow of foreign exchange losses and costs booked for new plants in Mexico and Thailand.
Shares in Japan's fifth-biggest automaker rose more than 5 percent after it said on Thursday April-June operating profit was 53.32 billion yen ($430 million). That was down from 56.38 billion yen a year ago, but above an average estimate of 51.24 billion yen in a survey of 10 analysts by Thomson Reuters.
New model launches helped sales in China surge 31 percent to a record 57,000 vehicles, helped partly by government incentives favouring the environmentally-friendly Mazda3 model. But the automaker remained cautious on China, as concerns linger on whether recent stock market turmoil and economic jitters might squeeze consumers' appetite for new cars.
"To be honest, it's difficult to read (the Chinese auto market)," said Masahiro Moro, managing executive officer and head of global marketing. "Up to now it's been growth and growth, but that's no longer quite the case," he said.
Mazda's global sales in its fiscal first quarter jumped 16 percent to 370,000, helped by brisk demand for the remodelled Mazda2 and CX-3 vehicles. Sales in North America, its biggest market, rose 5.6 percent.
The sales boost took the sting out of depreciation costs of 5.6 billion yen booked for new plants, and 10.8 billion in foreign exchange losses. Mazda's shares closed up 4.2 percent, while the benchmark Nikkei index ended 1 percent higher.
Mazda left its financial forecasts for the year ending March 2016 unchanged, projecting operating profit of 210 billion yen, slightly up from 203 billion yen a year earlier.
$1 = 124.1400 yen Reporting by Minami Funakoshi; Editing by Kenneth Maxwell