* Nore than 20 deals agreed
* Modi seeking to rebuild after Bihar vote loss
* Protesters call for end to religious persecution (Adds more than 9 billion pounds of commercial deals)
By Kylie MacLellan and Lisa Barrington
LONDON, Nov 13 (Reuters) - Britain and India welcomed more than 9 billion pounds ($13.7 billion) in commercial deals during a visit by Indian Prime Minister Narendra Modi, but his arrival was overshadowed by protests over a perceived rise in intolerance back home.
Modi got a warm welcome by British Prime Minister David Cameron, who has tried to cultivate closer ties with India to secure business opportunities in a fast-growing economy at a time when Modi has been prioritising other relationships.
For his part, Modi is seeking to restore his authority on the world stage after a defeat for his Hindu nationalist party in populous Bihar state on Sunday. He appealed to business to invest in a more transparent India in a speech at the Guildhall, a historic building in the heart of London's financial district.
While Cameron said he wanted to support Modi in his efforts to transform India with improved infrastructure, the Indian leader signalled he wanted Britain to stay in the European Union, saying the country was India's gateway to Europe.
"We want to become your number one partner for supporting the finance needed for this ambitious plan, making London the world's centre for offshore rupee trading," Cameron told him during a news conference, adding that plans were in place to issue more than 1 billion pounds in bonds.
He later said in a statement: "During this visit, British and Indian companies are announcing new collaborations, together worth more than £9 billion pounds."
The British government listed more than 20 deals and collaborations, including a 1.3 billion-pound ($1.98 billion) investment by Vodafone.
The two prime ministers also welcomed a package to promote clean energy worth 3.2 billion pounds of commercial agreements, joint research programmes and initiatives to share technical, scientific, and financial and policy expertise.
Before the visit, diplomats said the Indian leader was keen to buy 20 more BAE Systems Hawk trainer aircraft to be made in Bengaluru.
Cameron has visited India three times since taking office in 2010 to try to climb up the diplomatic pecking order, but Modi is the first Indian head of government to pay an official visit to Britain, the country's former colonial ruler, in almost a decade.
His visit comes at a time when a debate is raging in India over accusations that Modi is failing to rein in Hindu zealots trying to impose their values on all Indians.