UPDATE 2-Russian shares slump in London, Moscow shut again

* FTSE Russia IOB index of GDRs down 10.2 percent

* Russian bourses stay closed, RTS still down 21 pct on week

* Regulator says exchanges may not open on Monday

(Adds London-listed shares, close, rouble, quotes)

MOSCOW, Oct 10 (Reuters) - Russian Global Depositary Receipts (GDRs) fell in line with a collapsing global stock market on Friday, while Moscow's bourses remained shut by order of the markets watchdog.

The FTSE Russia IOB index .FTRIOB, which contains some of the most liquid Russian GDRs, closed down 10.2 percent on the day, shrugging off news that Russia could start buying shares to support the market in the next few days. [ID:nLA314643]

The share purchases are part of Russia's $210 billion market rescue package, but analysts say the global financial market situation needs to stabilise before confidence returns.

Moscow's bourses did not open on Friday, but that did not stop them from recording their worst weekly performance in a since the 1998 financial crisis.

The benchmark RTS index has lost 21 percent this week , while the MICEX, an indicator of more liquid rouble trade slumped over 24 percent .

"Thank goodness we're closed today," Alfa Bank said.

The MICEX exchange plans to resume trade on Monday, Oct. 13, an exchange official said, but the head of Russia's market watchdog, Vladimir Milovidov, said he was still weighing options.

"As far as the next several days are concerned, we will have a look on Monday and act to prevent uneconomic actions and exceses panic, especially since the issue of trade suspension is under discussion not only here, but in the West," Milovidov said.

Of the Russian companies traded in London, steel group Evraz (HK1q.L) lost 23 percent as its sector battled a sharp reduction in orders from the construction and automotive sectors.

Miner Norilsk Nickel (NKELyq.L), part owned by cash-strapped Russian billionaire Oleg Deripaska, fell 7.7 percent.

Russia's largest oil company, Rosneft (ROSNq.L) fell 13 percent, while the price of oil fell 4 percent CLc1.

"People are still trading over the counter," Da Vinci Capital hedge fund manager Gleb Yakovlev said. "It can only stop the execution of margin calls."