South Africa is unyielding to stiff pressure from the United States (U.S.) for reduction of its business transactions with Iran, but has instead increased its import of crude oil from the south-western Asian country.

Latest customs data reveal that South African crude oil imports from Iran swelled from 2.8b rand in February to 3.37b rand ($434.8m) the month after. It also indicated that 505,908 tonnes of Iranian crude was imported in March, up from 417,188 tonnes the previous month.

The country’s foreign ministry and the department of energy have kept mum on the development — a slight progress from the situation in March, when senior energy and foreign ministry officials gave conflicting figures on the status of Iranian imports.

Africa’s biggest economy had been under considerable Western pressure to slash crude imports from the Islamic country as one of a lengthy list of sanctions designed to crush Tehran’s apparent hunt for nuclear weapons, but a diplomatically stolid Pretoria has not minced words in looking the other way, despite knowing it itself risks economic hit from the West should the trend continue. Although its crude imports from Iran dropped between October 2011 and January 2012, they began increasing again in February.

The revelation from the Revenue Service questions the sincerity of the southern African country’s refiners, most of whom recently claimed to have found alternative suppliers to Iran, which until late last year,  was typically the country’s biggest crude supplier, accounting for a quarter of its oil imports.

Engen, the biggest South African buyer of Iranian crude, majority-owned by Petronas, a Malaysian state oil group, led the pack in April when it announced its termination of importation of Iranian oil. Petrochemicals group Sasol, which collected 12,000 barrels of Iranian oil per day, made similar claim albeit it failed to name its new supplier. Two months earlier, BP and Chevron had said they were not sourcing any Iranian crude.

In March, South Africa’s crude imports totalled 1.6m tonnes, Nigeria supplying 38 per cent, Iran 32 per cent, Saudi Arabia 22, and Angola the rest.

As has already become evident, South Africa’s assent to U.S.’s wish will be anything but easy, as some of its refineries are specifically designed to treat Iranian-type crude only, and refiners would have a hard time replacing them with other products.

Similarly, any disruption in crude imports could truncate fluid fuel supplies already shortened by strikes and refinery problems.