Foreign multinationals in 2014 booked more profits in tiny Bermuda than in China, the UN revealed in a report Tuesday likely to bolster growing international outrage over the lack of financial transparency.

The United Nations Conference on Trade and Development (UNCTAD) decried that multinational corporations appeared to be booking income disproportionately in "low tax, often offshore, jurisdictions".

The report seems to confirm techniques brought to light in the "Panama Papers" leak, in which some large companies report profits in low-tax jurisdictions in a bid to skirt taxes in the countries where they actually carry out their activities.

The UNCTAD study showed for instance that multinationals from a sample of 26 developed countries registered $43.7 billion in profits in tax haven Bermuda in 2014 -- or 779 percent of the territory's gross domestic product.

By comparison, they booked only $36.4 billion in income in China, corresponding to 0.3 percent of the country's GDP.

"How is it possible that in Bermuda you have more profit declared than in China?" said Astrit Sulstarova, who heads UNCTAD's Investment Trends unit.

"It seems that there is something that is fishy there," he told AFP.

Revelations in the so-called Panama Papers leak last month showed how one law firm set up 200,000 offshore entities for wealthy clients around the globe, throwing the secretive financial sector in Panama and other offshore tax havens under intense international scrutiny.

The UNCTAD report also showed that foreign multinationals booked more than $30 billion in income in the Cayman Islands, amounting to 875 percent of GDP.

More than $74 billion in income was meanwhile booked by foreign multinationals in Luxembourg, the world's primary recipient of investment flows from so-called special purpose entities (SPEs) -- basically shell companies.

That is equivalent to 114 percent of the country's GDP, UNCTAD said.

- Surging volumes -

Tuesday's report also showed that the volume of investment flows through SPEs, which in addition to Luxembourg are mainly based in the Netherlands, surged in 2015.

Due to massive volatility, with the flows swinging violently between large-scale investments and divestments, the annual total value landed down slightly at $221 billion, UNCTAD said.

Offshore financial centres in the British Virgin Islands and the Cayman Islands meanwhile raked in a total of $72 billion in investments last year, which is down from the record $78 billion seen in 2013, but still quite high, Sulstarova said.

While multinational corporations from developed economies, and especially the United States, traditionally dominated investments going in and out of these offshore jurisdictions, UNCTAD's report shows that developing economies now in fact account for a majority of the money flowing through there.

Between 2010 and 2014, companies from China, Hong Kong, Russia and Brazil accounted for 65 percent of the investment flows in the Caribbean's main financial centres.

The report warned over "the potential for a substantial disconnect between productive investments and income generation by (multinationals)," cautioning this had "implications for sustainable development" in the economies were goods and services are produced.