* More than 7.3 million forms arrive from UK
* UN monitors say vote can be credible
By Jeremy Clarke
JUBA, Sudan, Dec 22 (Reuters) - Millions of ballot papers were delivered to south Sudan on Wednesday, removing one uncertainty ahead of a referendum on southern independence scheduled for next month.
The Jan. 9 referendum has been fraught with delays and logistical problems, and organisers had feared snowy weather that has snarled air traffic in Britain might stop English printers from delivering the forms on time.
People from the oil-producing but underdeveloped south are widely expected to choose independence in the vote.
The plane carrying more than 7.3 million ballot forms landed in the airport in the southern capital Juba and was surrounded by security forces, U.N. officials and a Reuters witness said.
"You cannot control winter, but this is what we believed would happen and it has. The ballots will be produced on time," said Anne Itto, a senior official with south Sudan&${esc.hash}39;s ruling party, the Sudan People&${esc.hash}39;s Liberation Movement.
"All other complaints are minor now, the main thing is the ballots are here and the referendum can go ahead."
The referendum was promised in a 2005 peace deal that ended decades of north-south civil war and analysts have warned disagreements over the vote could reignite conflict.
The north&${esc.hash}39;s dominant National Congress Party is backing unity, but denies accusations from southern leaders it just wants to keep control of southern oil.
U.N. referendum monitors on Wednesday praised the commission but said they still faced a number of challenges, including funding shortages and lawsuits.
"(The organisers) have faced financial and logistical hurdles and yet voter registration was largely peaceful, orderly and transparent ... Based on our observations so far, we believe that a credible referendum can take place," said former Tanzanian president Benjamin Mkapa, heading the panel.
A number of civic groups in the north have launched legal challenges with the country&${esc.hash}39;s Constitutional Court, calling for the organising commission to be dissolved and voter registration to be re-run. (Additional reporting by Andrew Heavens in Khartoum, Editing by Sonya Hepinstall)
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