Tokyo stocks opened flat on Monday after three days of gains, as cautious investors watched developments in the FBI probe into alleged Russian meddling in the US election.

The benchmark Nikkei 225 index was up 0.01 percent, or 2.94 points, at 22,821.97 in early trade while the broader Topix index gained 0.16 percent, or 2.92 points, to 1,799.45.

It will be "a week of patience" as investors keep a wary eye on US political developments and economic indicators, Okasan Online Securities said in a note.

But a weaker yen, which is positive for Japanese exporters, helped prop up the market.