Export of U.S. weapons abroad soared more than three times the previous level in 2011, at least partly because of the continuing tensions over Iran's disputed nuclear program in the Persian Gulf region.

From $21.4 billion of sales in 2010 the total for last year reached $66.3 billion, the largest for a single year in the history of the U.S. arms export program, the report by the U.S. Congress Research Service said.

Analysts said the report contrasted with industry reports through most of 2011-12, which said the year would be marked by major downturns in weapons purchases worldwide. Fear of an arms sales slump prompted many industries to start looking at cybersecurity and other security challenges as alternative areas of potential business growth.

Despite the report's upbeat results, the figures for weapons exports indicate that sales for U.S. rivals in the marketplace may not have been as impressive as originally expected.

Global weapons sales from all countries totaled about $85.3 billion, almost double the previous year's sales of $45.2 billion. With U.S. weapons exporters claiming the lion's share of those exports, the outlook for other exporters still needs to be determined.

The United States also ranked first in the value of arms deliveries worldwide, taking $16.2 billion of all global deliveries. The United States has led global arms deliveries for eight years running, the CRS report said.

Despite vigorous arms marketing Russia ranked a distant second to the United States in worldwide arms deliveries, earning $8.7 billion while Britain ranked third with earnings of $3 billion from weapons deliveries.

It wasn't clear if the report of global arms sales includes statistics for two major emergency arms transfers, in Libya and then in Syria. While in Libya much of the arms deployed were sourced by industry analysts to European suppliers, the arms traffic to Syria remains muddled amid continuing conflict in that country.

The CRS report excludes arms sales by private companies and traders that remain classified. It also doesn't include clandestine arms transfers by governments.

The leading buyer for U.S. weapons last year was Saudi Arabia, which began a military buildup in response to the crisis over Iran's disputed nuclear program and internal security challenges posed by a spillover of Arab Spring protests in the kingdom.

Saudi Arabia has been the leading developing world arms buyer from 2004-11, making arms transfer agreements that have totaled $75.7 billion during the period.

During the same period, India has been the second major buyer with arms purchases of $46.6 billion, followed by the United Arab Emirates with $20.3 billion, Egypt at $14.3 billion and Pakistan at $13.2 billion.