Kenya's striking teachers threatened with the sack

The school term will be extended to help students prepare for exams

Kenya's government has threatened to sack striking teachers and replace them with graduates and retired teachers if they do not return to work on Friday.

The ultimatum came after teaching unions rejected a government pay offer to end the three-week strike, which has closed public schools.

About 200,000 teachers are demanding a wage increase of between 100% and 300% - the pay rise offered was nearly 4%.

Meanwhile, lecturers have agreed a deal and universities will open on Monday.

'Mockery'

On Thursday, police used tear gas to disperse stone-throwing undergraduates angered by the strike.

Kenya's doctors are also taking industrial action, and public hospitals are only taking emergency cases.

The BBC's Noel Mwakugu in Nairobi says the rising cost of living and the selective approach the government has taken to award pay hikes to its workers has largely contributed to the strikes.

Some argue that the government has neglected priority sectors like education and health in favour of politicians and bureaucrats who earn huge salaries.

On Wednesday, the Kenya National Union of Teachers rejected the government pay offer as a "mockery", Kenya's Daily Nation newspaper reports.

In response, the cabinet said it would employ 100,000 newly graduated teachers and retired teachers under 65 years of age.

Ministers also agreed to extend the school term by three weeks to 23 November to allow students to make up for lost time in preparing for end-of-year exams.

Correspondents say threatening to sack striking civil servants is a common tactic.

In the last year, the government has threatened to fire state broadcasters and nurses and advertised their posts in the newspapers.

However the disputes were resolved and no jobs were lost.