* Al Shabaab claim responsibility for attacks
* Somali group says frees suspects from cells
* Similar raids last month stoked political tensions
* Deputy president suggests political rivals to blame (Adds comments by deputy president)
By Joseph Akwiri
MOMBASA, Kenya, July 6 (Reuters) - Gunmen killed at least 29 people in two coastal areas of Kenya in raids the deputy president indicated on Sunday were the work of political rivals, despite Somali Islamists al Shabaab claiming responsibility.
The raids will hammer Kenya's beleaguered tourist industry after a wave of militant attacks and will deepen public frustrations about poor security, a day before a big opposition rally in the capital.
The Interior Ministry said one of the Saturday night attacks killed nine in the trading town of Hindi in Lamu County, close to where 65 people were killed by gunmen last month in Mpeketoni.
Another was further south in the Gamba area, where 20 died.
"They went around shooting at people and villages indiscriminately," said Abdallah Shahasi, a senior official for the Hindi area, which lies near the old trading port of Lamu.
Militant raids on the coast have fanned an already tense political atmosphere in Kenya, which has sent troops to join African Union soldiers battling al Shabaab in neighbouring Somalia.
Sheikh Abdiasis Abu Musab, spokesman for the military operations of al Shabaab, told Reuters in Mogadishu the group was behind both attacks.
The group, which attacked Westgate shopping mall in Nairobi last year killing 67 people, had also said it was responsible for the Mpeketoni attacks.
But, just as President Uhuru Kenyatta dismissed al Shabaab's claim last month and pointed the finger at local politicians over Mpeketoni, his deputy on Sunday suggested political rivals were again to blame.
"We want to tell our friends they cannot blackmail us using criminal elements in our country," Deputy President William Ruto said on a visit to the Lamu area. He offered no names.
"If you are unable to wait for the next general election, you are in a hurry, you want to make the country ungovernable so you can get into office through the backdoor, that will not happen in Kenya," he said. "You can forget about it."
The comments are likely to stoke an already fierce row with the opposition, which has denied any role.
Police Deputy Inspector General Grace Kaindi also cast doubt on al Shabaab's role, saying a blackboard ripped from a school, scrawled with slogans and placed at a junction near Hindi could implicate the separatist Mombasa Republic Movement (MRC).
"At first we thought it was al Shabaab, but now it is turning out that it is MRC as they have put it there clearly," she told a news conference.
She said other scribbled phrases seemed to back opposition leader Raila Odinga.
Slogans included "MRC - You are sleeping", "Muslims your land is being grabbed", "Raila is adequate" and "Uhuru down".
The MRC swiftly denied any role.
"The government should stop using us as a scapegoat," Randu Nzai Ruwa, the MRC Secretary General, told Reuters by telephone.
Veteran opposition leader Odinga, defeated by Kenyatta in last year's election, has held rallies over the past month criticising the government over frequent militant attacks.
He planned to hold a major rally on Monday in Nairobi.
Police said attackers hit government offices and burnt a church in Hindi during the latest raids.
Lamu County police chief Ephantus Kariuki told Reuters victims were shot in the head with their hands bound, and said the attack could have been prompted by land disputes between rival ethnic groups on the coast.
Al Shabaab claimed it had broken into the police station at Gamba during the raid on Saturday and freed suspects from detention cells.
A police source corroborated that account, saying the numbers for those released was still being checked. Gamba lies in Tana River County, which neighbours Lamu County.
"They killed some of our colleagues and freed Muslim detainees," the source told Reuters. "Some of those freed were linked to the Mpeketoni attacks two weeks ago."
In a separate criminal incident in the port city of Mombasa, a Russian woman tourist who was with two companions was killed by a gang, which robbed them, police said. (Additional reporting by Feisal Omar in Mogadishu; Writing by Duncan Miriri and Edmund Blair; Editing by William Hardy, Stephen Powell and Sophie Hares)