President Vladimir Putin

Mr Putin said: "We can say with certainty that the party has achieved a very good result."

The nationalist LDPR and the Communist party are way behind United Russia, with about 14-16% each.

Liberal opposition parties appear to have failed to pass the 5% threshold needed for party-list representation.

However, the exit polls say though they could still get seats in individual constituencies.

A VTsIOM exit poll gave United Russia, led by Prime Minister Dmitry Medvedev, 44.5%, with the Public Opinion Foundation putting its total higher, at 48.7%.

It is Mr Erdogan's first foreign visit since an attempted coup last month.

Relations between the two countries were plunged into crisis last year when Turkey shot down a Russian military jet on the Syrian border.

The visit comes as Turkey's ties with the West have cooled over criticism of a crackdown on alleged coup-plotters.

Before leaving Turkey, Mr Erdogan referred to President Putin as his "friend" and said he wanted to open a new page in relations with Russia.