Image copyright Reuters Image caption Japan, Iran's second biggest oil customer, will reduce its imports, says finance minister Jun Azumi

Japan will take "concrete steps" to reduce its oil dependency on Iran, its finance minister has announced.

The comments from Jun Azumi came after he met US Treasury Secretary Timothy Geithner in Tokyo.

Mr Geithner is seeking backing from China and Japan for stricter sanctions on Iran's oil industry in a bid to curb Tehran's nuclear ambitions.

On Wednesday he raised the issue with Chinese leaders in Beijing, but did not get the same public support.

"In the past five years, we have reduced... the amount of oil imported (from Iran)," Mr Azumi said during a joint press conference with Mr Geithner.

"We wish to take planned and concrete steps to further reduce this share, which now stands at 10%."

Japan is the second biggest customer for Iranian oil, and has already urged Gulf Arab countries to increase their exports to make up any shortfall.

The supplies are badly needed as it is using increasing amounts of thermal power to generate electricity because of the nuclear crisis at Fukushima.

Mr Geithner welcomed the Japanese response.

''We are working very closely with Europe and Japan and allies around the world to substantially increase the amount of pressure we bring on Iran,'' he said.

"We very much appreciate the support Japan has provided standing with us and the international community in support of this very important strategic objective."

China: 'Stress co-operation'

Mr Geithner's visit to East Asia comes amid international tension after the UN's nuclear watchdog said Iran had begun enriching uranium to a higher grade than is needed for power generation.

The US has accused Iran of "blatant disregard for its responsibilities".

On New Year's eve, US President Barack Obama authorised a law imposing sanctions on financial institutions dealing with Iran's central bank, which is responsible for processing most oil purchases.

In Beijing, Mr Geithner met Premier Wen Jiabao, Vice-President Xi Jinping and Vice-Premier Li Keqiang on Wednesday and counterpart Vice Premier Wang Qishan on Tuesday night.

While China did not voice support for US sanctions on Iran, it said that it hoped that Tehran and the International Atomic Energy Agency would "stress co-operation".

It also reiterated that its oil trade with Iran should not be linked to the nuclear issue.

"To place one country's domestic law above international law and press others to obey is not reasonable," ministry spokesman Liu Weimin told reporters at a regular briefing.

China buys almost a third of Iran's oil exports and has rejected what it calls US unilateral action against Tehran in the past.

Chinese Premier Wen Jiabao is scheduled to visit the oil and gas producing countries of Saudi Arabia, Qatar and the United Arab Emirates this weekend - a sign that China may be seeking other options for its energy supply.

Amid escalating tensions over Iran's nuclear programme, an Iranian nuclear scientist was killed by a magnet bomb fixed to his car by a motorcyclist. Tehran has blamed Israel for the attack.

Iran says its nuclear programme is for power generation purposes only.