By Jonathan Saul

LONDON Ukraine's move to create a shipping channel for grain exports is a positive step for global food security, although efforts continue to reach a new agreement over a broader Black Sea corridor, the top U.N. trade official said on Wednesday.

Russia in July quit a U.N.-backed deal which had enabled exports from Ukraine to sail from three approved ports.

Since then, Kyiv has launched what it calls a temporary humanitarian corridor in an effort to break Russia's de facto blockade. Two ships have sailed in recent days from the Ukrainian port of Chornomorsk using the channel, which hugs the Romanian and Bulgarian coasts.

"We see the alternatives that are being explored to export in a very positive light because the important thing is to get the grain to global markets," Rebeca Grynspan, who leads the implementation of the U.N. deal with Russia, told Reuters on the sidelines of a U.N. event in London.

Grynspan said while the new corridor that Ukraine is trying to open is among “very important efforts”, she added that "the risks are higher".

"The only thing that will take the risk away and stabilise ... the situation is an agreement that will be backed by all partners," she said, adding she was unable to provide any timeframe for a deal.

Elsewhere Lloyd's of London is in talks with the U.N. over providing insurance cover for Ukrainian grain shipments if a new Black Sea corridor deal can be reached, its CEO John Neal told Reuters this month.

Grynspan said "options are being discussed", adding that "insurance is a big part of the solution".

Russia's Foreign Minister Sergei Lavrov said on Sept. 23 that while Moscow does not reject U.N. efforts to revive the Black Sea grain deal, a recent proposal by U.N. Secretary-General Antonio Guterres was unrealistic.

Grynspan said the U.N. did not agree with this assessment.

"We are convinced that we put forward real solutions to the issues that Russia has raised. We want to have the possibility to still explain why we think that these are real solutions," she said.

Grynspan told Reuters in May that the U.N. was working with the African Export-Import Bank to create a platform to help process transactions for Russian exports of grain and fertilizer to Africa.

She said on Wednesday that even for Russian banks that had not been cut off from the SWIFT international payments system or had sanctions imposed, "due diligence is a problem".

"We are putting forward platforms and solutions for these problems - that are problems of procedure, risk aversion in the private sector that we need to solve."

(Reporting by Jonathan Saul; Editing by David Holmes)