MOSCOW: The rouble firmed close to a four-week high in early trade on Tuesday, supported by higher oil prices and investor optimism ahead of a meeting between the presidents of Russia and the United States.

At 0815 GMT, the rouble was 0.1 percent stronger against the dollar at 62.43, having briefly touched 62.37 - its highest since June 14. It gained 0.18 percent to 73.32 versus the euro.

Brent crude oil, a global benchmark for Russia's main export, was up 1 percent to $78.84 a barrel.

Societe Generale expects oil prices to remain "comfortably high" in the coming months and hover at $78-80 by the end of the year, its Russian unit Rosbank said.

"For the rouble rate, this situation ... means hope for the absence of negative shocks, at least from the oil market," Rosbank said in a note.

Rouble gains are capped by regular forex purchases for Russian state reserves, planned for July 6-Aug 6 at the equivalent of 347.7 billion roubles ($5.57 billion).

The rouble is probably also being underpinned by positive investor expectations ahead of the July 16 meeting between Donald Trump and Vladimir Putin in Finland, analysts at BCS brokerage said in a note.

Russian stock indexes were mixed.

The dollar-denominated RTS index was up 0.1 percent to 1,194.50 points. The rouble-based MOEX Russian index was 0.24 percent lower at 2,367.86 points.