Channel Seven has dumped Today Tonight in Sydney, Melbourne and Brisbane, replacing the tabloid current affairs show with a one-hour news service.

But the 19-year-old program has been spared the axe in Adelaide and Perth, where it still wins the 6.30pm time slot against arch-rival Nine.

No more Today Tonight: Acting host Nick Etchells will be placed elsewhere within Seven News, according to chiefs.

Seven will launch its extended news tonight. All Today Tonight staff on the east coast have been redeployed to make "news investigations and features" for the bulletin.

Seven's announcement follows Nine's move to a national one-hour bulletin at the start of this year, with A Current Affair moving to 7pm.