By Mike Wooldridge BBC World affairs correspondent, Malta

President Museveni has found himself centre stage in Malta

The Commonwealth is often described as a club.

And as the Malta summit got under way it seemed to have another case on its hands of a club member breaking the rules.

Uganda was once synonymous with brutal dictatorship.

Since then it has been held up as an example of a country enjoying a fair measure of success in burying its notoriety as a failed state.

But now the main opposition leader, Kizza Besigye, has appeared before a military court to face a charge of terrorism, as well as a charge of treason in the civilian courts.

Aside from anything else, the timing seemed surprising - just as Uganda would presumably want to reassure its Commonwealth partners that their decision to hold the next Commonwealth summit in Uganda was justified.

And Uganda must surely have known, you hear people saying here, that a politician appearing in a military court does not exactly square with the new democracy in Africa.

No remorse

So here was the Commonwealth summit trying to focus on crucial issues like global trade reforms and how to build more tolerant societies, now at risk of having its agenda hijacked by events in one country.

Some leaders appear to have conveyed their feelings strongly, others probably less so Ugandan press concerned

Suddenly, as an official put it, the issue of Uganda was catching fire.

One chosen tack was to encourage President Yoweri Museveni to explain himself.

At a news conference Mr Museveni flatly denied that he was trying to prevent Kizza Besigye challenging him at the polls next year.

He said he had been sent to a military court because alleged terrorist activities fell under the Armed Forces Act.

And he suggested that his government should be acclaimed by the Commonwealth because it had ended a long-running culture of impunity.

Zimbabwe parallel

The Ugandan opposition was demanding more than this.

Kizza Besigye and his wife are both former allies of President Museveni

It wanted tough Commonwealth action in an attempt to get its leader released. It is not clear at this stage whether the Commonwealth will actually do anything more than watch developments.

Some leaders appear to have conveyed their feelings strongly, others probably less so.

There seems to be a hope that Mr Museveni's keenness to host the next summit will have its own impact on his future actions.

But the Commonwealth will clearly not want to be left wringing its hands over Uganda in the way it seems to have been over Zimbabwe.