(Adds comment from tin exporter association, PT Timah in paragraphs 9-12)

JAKARTA, Oct 20 (Reuters) - Indonesia has yet to decide the timing of a possible ban on tin exports and is still making calculations about its impact, President Joko Widodo said on Thursday, as the southeast Asian nation pushes to step up domestic processing.

The world's top tin exporter, Indonesia has already moved to halt shipments of a number of other metals in order to develop more processing at home. It now exports about 95% of its tin production.

Jokowi, as the president is known, said the government wanted to avoid any financial losses that companies may face from a ban but stressed authorities would steer the mining industry towards more domestic downstreaming.

"Everything must go into industrial downstreaming because the added value is there," he told reporters in a streamed video, after visiting a smelter in the tin mining hub of Bangka Belitung.

On Wednesday, a mining ministry official said the government was collecting data on what processing industry Indonesia would need to mop up its own production of the metal, should it decide on the export ban.

"We have not decided when we will stop exporting tin raw materials," Jokowi said. "We will calculate everything so that everything goes well, no one is going be at a loss."

Indonesia exported 74,671.57 tonnes of tin metals in 2021, worth $2.42 billion, in the form of pure bars, solder bars and wires, trade ministry data showed.

From January to September it had exported 58,178.69 tonnes of tin metals to markets such as China, Singapore, South Korea and others in Europe.

The government has asked industry for its input and the industry would support the government's programme to increase value addition in the tin industry at home, Jabin Sufianto, secretary general of Association of Indonesian Tin Exporters said.

"We have provided available data for the government to create a roadmap for downstreaming that can benefit the state and businesess," Jabin said.

State tin miner PT Timah, one of the world's biggest refiners, has developed various downstream tin products including tin chemical and soldering in the past years, chief executive Achmad Ardianto said in a statement.

On Thursday, President Jokowi visited the construction site of PT Timah's Ausmelt furnace which is expected to be completed in November and will be able to process lower grade tin ore. It will have an output capacity of 35,000 tonnes tin ingots annually.

Investment ministry official Heldy Satrya Putera said potential investors in the sector had expressed interest after being approached by the government, but declined to give more details.

He said the government would come up with a road map for investment, which it would prefer to steer into industries that offer the best prospects for value addition. (Reporting by Fransiska Nangoy, Bernadette Christina Munthe; Editing by Martin Petty, Clarence Fernandez and Kim Coghill)