The American missionary who has become one of the first victims of the country's clampdown on religion has lost an appeal against his conviction.

But Don Ossewaarde intends to fight on and take the case to a higher court.

Ossewaarde was charged under Russia's so-called Yarovaya Law, signed by President Vladimir Putin on July 7. Named after one of its creators, Irina Yarovaya, it's a sweeping expansion of anti-terror and public safety measures. Among its provisions are a draconian clampdown on evangelism and missionary activity.

Ossewaarde was fined 40,000 roubles (around $700) after being accused of proselytising in Oryol, the town where he and his wife Ruth have lived for 14 years.

At a hearing on Friday he told the judge he had read the relevant law carefully for what constituted prohibited "missionary activity". "Even though Russian is not my native tongue, even I was able to understand that my activity does not meet this definition, so I have not broken any laws. I am exercising the rights guaranteed by the constitution and the laws of the Russian Federation," he said.

However, the judge found against Ossewaarde.

In a website update he said: "Now we have to take it to the next level of appeal, which is probably going to be here in Oryol. The lawyer does not expect anything to change until we get past the local system, and can get into the upper level courts in Moscow. I assured him that I would keep pressing the appeal all the way to the highest court, and he assured me that this case will play an important role in determining the future of religious freedom in Russia, not just for foreign missionaries, but also for ordinary Russian believers."

Ossewaarde said: "Obviously, this is a disappointment. I was hoping to wrap things up here and return to my family as soon as possible, but the issue is an important one, and duty demands that I press the case as far as I can."

He asked supporters to continue to pray for him.