Adelaide bus drivers are considering strike action over demands for higher pay and improved safety.

Drivers are concerned over a recent spate of assaults and want companies to take action to keep them safer on the job.

The Transport Workers Union has dismissed a 2.8 per cent pay rise offer from bus companies, asking instead for five per cent.

It has written to members asking them to vote on industrial action including refusing to collect fares, overtime bans and rolling 24-hour strikes.

The ballot will close on January 21.

Union state secretary Ray Wyatt says industrial action may result in major disruption across the metropolitan bus network.

The State Government says it is hopeful bus operators and drivers can come to an agreement on pay.

The government has also responded recently to safety concerns by tasking transit police to target major bus routes and bus interchanges across the city.

The South Australian Opposition says the threatened industrial action follows two years of disappointing bus services and rail closures.