The company said it has seen little real impact from the crisis in Japan, its second-largest customer.

“We’ve seen some impacts to individual shipments of some of our products, but they have almost entirely been offset by continued strength in the Chinese markets,” Chief Executive Tom Albanese said after the group’s annual meeting.

Supply of equipment, such as trucks or parts, made by Japanese companies had been disrupted but the company was able to get around that.

“While there have been areas where we’ve seen some short-term impacts, they have not been material and they have not had a material impact on the business,” Albanese said.

Rio still sees financial markets as fragile due to economic and financial imbalances, Rio Chairman Jan du Plessis said, reiterating comments from the group’s annual meeting last month in London.

“However our pursuit of operational excellence and our strong balance sheet put us in a positive position to weather this short-term volatility.”

After struggling through the global financial crisis and paying down $40 billion in debt that it took on for its ill-timed acquisition of Alcan in 2007, Rio recently secured an upgrade in its credit rating from Standard & Poor’s to single A, following an upgrade from Moody’s.

Following a record profit for 2010, the company launched a $5 billion share buyback, of which it has bought back about $1.3 billion worth of its UK listed shares so far.

Du Plessis said the company would consider further buybacks once this one is completed, but said a buyback of its Australian shares was unlikely in the near term as the Australian shares were more expensive than its UK shares.

With low debt and soaring cash flows, Rio is back on the hunt for acquisitions, but has made clear it is only interested in small- to mid-size deals, worth less than $10 billion, in order not to stretch its balance sheet too much.

“That’s a low-risk, sensible way to add value,” du Plessis said.

Rio’s shares were up 0.4 percent at A$81.21 outpacing a 0.2 percent gain in the broader market .

Albanese dismissed speculation which roiled the market on Tuesday that Rio Tinto was lining up a bid for top North American aluminum producer Alcoa , highlighting that it would not fit with the smaller size of deals it would look at.

“I’ve seen some what I’d call ‘trader chatter’ over the past day or two and it sort of disappeared as quickly as it emerged. I thought that spoke for itself,” Albanese told reporters.

Rio won 73 percent control of Mozambique-focused Riversdale Mining last month with a A$4 billion takeover offer and has said it is looking to expand further in Africa.

Albanese and du Plessis declined to comment on whether Rio has held any talks with state-owned China Guangdong Nuclear Power about its planned bid for uranium explorer Kalahari Minerals .

Kalahari’s main asset is a 43 percent stake in Extract Resources , which owns the Husab uranium project which Rio has been looking to jointly develop with its own Rossing uranium mine in Namibia.

Rio owns 14 percent stakes in both Kalahari and Extract.

CGNPC trimmed its planned bid for Kalahari this week, but was blocked by UK regulators from going ahead with the bid as it was lower than initially proposed in March.

Investors have said Rio Tinto may be willing to work with CGNPC, given it has been building closer ties with the Chinese.

Its biggest shareholder Chinalco’s Chalco unit is set to become a partner in the Simandou iron ore project in Guinea, following Rio’s recent $700 million settlement of all disputes on blocks 3 and 4 of the Simandou concession.

“I was quite pleased with the level of support we received from Chalco and Chinalco,” Albanese said when asked how important the Chinese role was in securing the settlement with Guinea.

Rio, along with other coal miners, was hit by heavy rains and flooding in Queensland which led to it declaring force majeure on production from key coal mines.

Force majeure has been lifted on all but one mine, Hail Creek, and Albanese said it was not clear yet when it could be lifted there.