SINGAPORE  (Reuters) - Most Asian stocks struggled higher on Monday but investors were rattled by news that the FBI is planning to review more emails

related to Democratic presidential candidate Hillary Clinton's private server, just a week before the election.
European markets also looked set for a shaky start, with financial spreadbetter CMC Markets expecting Britain's FTSE 100, France's CAC 40 and Germany's DAX <.gdaxi to all open down percent.> Federal investigators have secured a warrant to examine newly discovered emails, a source familiar with the matter said on Sunday.
Clinton had opened a recent lead over her unpredictable Republican rival Donald Trump in national polls, but it had been narrowing even before the email controversy resurfaced. An ABC News/Washington Post poll released on Sunday showed Clinton with a statistically insignificant 1-point national lead.
The Mexican peso, which strengthens along with the chances for a Clinton win, remained weak, while the U.S. dollar edged up against other major currencies.
"There seems little doubt that a Trump victory would trigger selling in stock markets from current levels," Rick Spooner, chief market analyst at CMC Markets in Sydney, wrote in a note.
"This has traders nervous as they start the week assimilating fresh news on Hillary Clinton’s email problems."
MSCI's broadest index of Asia-Pacific shares outside Japan hit a six-week low on Monday before recovering 0.3 percent. It is set to end the month down 1.6 percent.
Japan's Nikkei, which touched a six-month high on Friday, closed 0.1 percent lower on Monday, but is up 5.9 percent in October.
Hong Kong's Hang Seng slid to a two-month low but revived to gain 0.2 percent, on track for a 1.35 percent loss in October. China's Shanghai Composite index fell 0.1 percent, paring gains this month to 3.2 percent.
On Friday, Wall Street and the dollar closed lower, after Federal Bureau of Investigation Director James Comey sent a letter to the U.S. Congress informing it that the agency is again reviewing emails related to the private server Clinton used when she was secretary of state.
Markets have tended to see Clinton as a candidate who will largely maintain the status quo, while there is greater uncertainty over what a victory for Trump might mean for U.S. foreign policy, international trade deals and the domestic economy.
Comey had decided in July that the FBI was not going to seek prosecution of Clinton for her handling of classified materials.