FACTORY export order books have weakened to their worst level since January 2013 partly as a result of political uncertainty at home and abroad, the CBI has said.

Its latest industrial trends survey of 488 manufacturers, carried out between August 20 and September 10, found output remained solid in the last quarter and should strengthen further in the coming three months.

But firms saw total order books fall below "normal" levels, with the impact on exporters particularly severe.

Economists said sterling's strength and the eurozone's continued economic stagnation were other factors, alongside the uncertainty caused by the Scottish referendum and the crisis in Ukraine.

CBI deputy director general Katja Hall said the export result was disappointing.