* Russian banking sector lost half of banks since mid-2013
* Three major bailouts are run by c.bank now
* C.bank to change requirements on provisions, access to funds (Adds details, quotes, background)
MOSCOW, Feb 2 (Reuters) - Russia's central bank believes a cleanup of Russian banks is more than half complete, Governor Elvira Nabiullina said on Friday.
Since Nabiullina took a helm at the central bank in mid-2013, the Russian banking system has lost around a half of its banks, with some collapsing and others taken over by the central bank in a bailout. The biggest examples were Otkritie, B&N and Promsvyazbank (PSB), seized by the central bank last year.
"We have passed through the majority of the clean-up of the banking sector from unqualified players," Nabiullina told an annual gathering of the country's bankers and the central bank on the outskirts of Moscow.
Under reforms introduced by Nabiullina, since mid-2017 only banks with strong ratings from the two Russian ratings agencies - ACRA and Expert RA - are eligible to gain access to some state funds and instruments.
Other rules were put in place requiring banks to meet additional capital requirements and have balance sheets of a minimum size to access state funds, but Nabiullina said these would be phased out to rely solely on the ratings agencies.
"Our rating agencies went through serious checks at the central bank, their methodology was verified... We can now rely on the rating agencies. And other criteria, linked to the scale of a bank or its ownership, will be gradually replaced," she said at the meeting on Friday.
To bail out just the three banks Otkritie, B&N and PSB, the central bank plans to spend around 1 trillion roubles ($17.82 billion). After the clean-up, Otkritie and B&N are to be sold and PSB turned over to the defence sector bank.
Otkritie, which was seized at the end of August, had seen a large outflow in client funds, partly caused by a low rating obtained from the Russian ratings agency ACRA.
Russia still has more than 500 banks. The Russian central bank has gradually tightened rules, including those governing lending to related parties or the banks' owners, seen as one of the reasons for bank failures and bailouts.
On Thursday, Nabiullina said that the central bank was discussing with banks a proposal to demand higher provisions for loans used for mergers and acquisitions rather than for regular business operations. ($1 = 56.1105 roubles) (writing by Katya Golubkova; Editing by Peter Graff)