Supporters of Kenyan opposition leader Raila Odinga run through the crowd prior to his arrival at a mass rally in the Shauri Moyo area of Nairobi, Kenya. Picture: AP Photo/Ben Curtis

Nairobi - Kenyan authorities will charge the sister of opposition leader Raila Odinga with incitement to violence after opposition supporters attacked officials from the election board last week, the chief prosecutor's office said on Monday.

Odinga has pulled out of the re-run of an election he was due to contest on Thursday against President Uhuru Kenyatta, saying problems with the election board meant the vote would not be fair. He has called for protests and a boycott and on Sunday said on Twitter there would be "no election".

"We resume our picketing at IEBC (election board) offices countrywide on Tuesday and Wednesday. We maintain that there will be no election on Thursday," he said, without giving details.

Kenya is East Africa's richest economy and a trade and transport gateway as well as a hub for diplomacy and security, so instability there quickly sends ripples through the rest of the region.

Last week Odinga's supporters disrupted a training session for election officials in the western city of Kisumu, which is his political stronghold. They attacked election staff and destroyed tents and polling material, witnesses said.

Ruth Odinga, who is the opposition leader's sister and a former deputy governor of Kisumu county, was present at the protest, according to Reuters witnesses. Prosecutors instructed police to arrest her, opposition Senator Fred Outa and others.

She will be charged with incitement, destruction of property, obstructing election officers and trespassing in an electoral centre, according to a letter that the director of public prosecution's office posted online.

"The suspects should immediately be charged," the letter said. Neither Ruth Odinga nor Outa could immediately be contacted for comment.

The arrests could anger Odinga's supporters and escalate tension over an election season that has divided the country and led to the deaths of at least 37 people since the first election was held on August 8, including four in the last two weeks.

Odinga says the election board had made insufficient reforms to prevent a repeat of the same mistakes that marred the previous presidential polls on August 8.

But the election board said it had addressed many of his complaints.

Kenyatta won that election but the Supreme Court nullified the result, saying there had been procedural irregularities and a repeat must be held.

The election board and Kenyatta say the poll will be held regardless of whether Odinga participates.

On Monday, 18 European countries, the European Union and the United States issued a joint statement calling on political leaders to talk to each other and pursue any protests peacefully.

"It would be a profoundly undemocratic act to try to interfere -- through intimidation or violence -- with an election held under Kenya's constitution," said British High Commissioner Nic Hailey.

U.S. ambassador Bob Godec said he was still holding out hope for a last minute deal that might persuade Odinga to take part in the polls.

"I continue to hope even now, there will be a last minute agreement .... that would unite the people of Kenya," he said.

The prolonged political uncertainty has helped blunt growth in the east African powerhouse and is partly responsible for the government trimming its annual growth forecast for this year from 5.9 percent to 5.5 percent. Last week, the central bank governor told Reuters it would be revised even lower.

On Monday, the Kenyan shilling dropped to 103.75/85 per dollar, its lowest level since mid-August, mainly due to concerns about potential violence during this week's polls, traders said.

They said the drop prompted the central bank to pump in dollars to curb the volatility. The shilling had ended Thursday's session at 103.20/40 per dollar. Markets were closed on Friday for a public holiday.

The yield on Kenya's $2 billion sovereign bond, maturing in 2024, has risen by 30 basis points since the nullification of the election on Sept. 1 to 6.306 percent as investors worry about the increased political risk.

On the Nairobi stock exchange, the blue-chip index of 20 top companies is down by 8.6 percent since the election results were cancelled, said Geoffrey Odundo, the chief executive officer of the Nairobi Stock Exchange.