UPDATE 2-UK stocks end lower on Sino-U.S. tensions, but mark monthly gains

* Rolls-Royce bottoms out FTSE 100 after S&P cuts to junk
* Investors await Trump news conference on China
* Discount retailer B&M rises on upbeat trading update
* FTSE 100, FTSE 250 gain for the month

(Adds details, updates to close)
By Sagarika Jaisinghani and Ambar Warrick
May 29 (Reuters) - UK shares ended lower on Friday as fears
of Washington's response to Beijing tightening its control over
Hong Kong tempered optimism over an eventual economic recovery
from the coronavirus crisis.
The blue-chip FTSE 100 .FTSE was down 2.3% with travel
.FTNMX5750 stocks serving as the top decliners, while the
mid-cap FTSE 250 .FTMC shed 1.7% to snap a nine-day winning
streak.
Still, the two indexes gained for the month as investors
continued to bet on a bounceback in economic growth from the
coronavirus.
Optimism over the reopening of a bulk of the British economy
next month saw the domestically inclined FTSE 250 marking its
best two-month rise since 2009.
For the day, bank stocks .FTNMX8350 tracked a decline in
gilt yields as investors fled to perceived safe havens ahead of
U.S. President Donald Trump's news conference on China's move to
impose a national security law on Hong Kong that has raised
concerns over its function as a global finance hub. "Global equities had been willing to look past the risk of
escalating U.S.-China tensions over recent weeks because the
threats had largely been confined to mere sabre-rattling," wrote
Han Tan, market analyst at FXTM.
"That Trump rhetoric is set to evolve into actual policies,
potentially in the form of sanctions, which could shatter the
stability that the world sorely needs in these early days of the
post-pandemic era."
The threat of a renewed U.S.-China trade war has stymied a
wider stock market rally, which had seen the FTSE climbing about
26% since mid-March, after crashing more than 36% from a January
record high.
Rolls-Royce RR.L tumbled nearly 15% to the bottom of the
FTSE 100 as Standard & Poor's cut its credit rating to junk on
the disruption to global air travel from the COVID-19 pandemic.

Discount retailer B&M BMEB.L rose 5.5% after an upbeat
trading update, while building materials supplier SIG Plc
SHI.L gained 4.3% on plans to raise 150 million pounds
($185.12 million) in new equity.