NEW YORK (REUTERS) - US manufacturing got off to a strong start this year, as rising domestic demand helped the sector grow this month at its fastest clip in nearly two years.

Financial information firm Markit said its US "flash", or preliminary, manufacturing purchasing managers index (PMI) rose to 56.1 this month, its best showing since March 2011. It stood at 54 last month. A reading above 50 indicates an expansion.

Output grew at its fastest pace since March last year, with the sub-index rising to 57.2 from 54.5 last month.

Firms tied the growth surge to higher demand from US customers, reflected by the index's new orders component, which rose to 57.7, the highest level since May of 2010.

Improved economic conditions in China and some parts of Europe also helped boost orders from abroad, the survey showed.

"However, it is the domestic market that is clearly providing the main impetus to the upturn," said Markit chief economist Chris Williamson.

Aggressive monetary stimulus from the Federal Reserve and a last-minute deal by Congress to avoid a year-end budget crisis and a large rise in taxes gave a boost to business confidence, Mr Williamson added.

Hiring also increased this month, with new jobs being created at the fastest pace in nine months, while average selling prices increased for a fifth consecutive month.