LISBON, Sha'ban 11, 1434, Jun 20, 2013, SPA -- Portugal must thoroughly investigate allegations of foreign bribery as its inaction raises serious concerns, especially over business with former colony Angola, the OECD warned on Thursday, according to Reuters. The Paris-based Organisation for Economic Cooperation and Development said in a report that since Portugal joined an international anti-bribery convention in 2001, only 15 bribery allegations had surfaced. None resulted in a single prosecution. Portugal signed up to combat bribery of foreign public officials in international business deals. The OECD said it had worked with Portuguese prosecutors to produce its assessment. Portugal has strong ties with its former colonies Brazil, Angola and Mozambique, all of them notorious for high corruption levels. Struck by a debt crisis and Europe's recession, bailed out Portugal has explored every opportunity to boost exports to these countries while attracting their investment to Portugal. -- SPA 19:42 LOCAL TIME 16:42 GMT www.spa.gov.sa/1122202